3 (three) is a

number
A number is a mathematical object used to count, measure, and label. The original examples are the natural numbers 1, 2, 3, 4, and so forth. Numbers can be represented in language with number words. More universally, individual numbers can ...

, numeral and digit. It is the natural number
In mathematics, the natural numbers are those numbers used for counting (as in "there are ''six'' coins on the table") and ordering (as in "this is the ''third'' largest city in the country").
Numbers used for counting are called ''Cardinal n ...

following 2 and preceding 4, and is the smallest odd prime number
A prime number (or a prime) is a natural number greater than 1 that is not a product of two smaller natural numbers. A natural number greater than 1 that is not prime is called a composite number. For example, 5 is prime because the only wa ...

and the only prime preceding a square number
In mathematics, a square number or perfect square is an integer that is the square (algebra), square of an integer; in other words, it is the multiplication, product of some integer with itself. For example, 9 is a square number, since it equals ...

. It has religious or cultural significance in many societies.
Evolution of the Arabic digit

The use of three lines to denote the number 3 occurred in many writing systems, including some (like Roman andChinese numerals
Chinese numerals are words and characters used to denote numbers in Chinese language, Chinese.
Today, speakers of Chinese use three written numeral systems: the system of Arabic numerals used worldwide, and two indigenous systems. The more fami ...

) that are still in use. That was also the original representation of 3 in the Brahmic
The Brahmic scripts, also known as Indic scripts, are a family of abugida writing systems. They are used throughout the Indian subcontinent, Southeast Asia and parts of East Asia. They are descended from the Brahmi script of ancient India ...

(Indian) numerical notation, its earliest forms aligned vertically. However, during the Gupta Empire
The Gupta Empire was an Outline of ancient India, ancient Indian empire which existed from the early 4th century CE to late 6th century CE. At its zenith, from approximately 319 to 467 CE, it covered much of the Indian subcontinent. This period ...

the sign was modified by the addition of a curve on each line. The Nāgarī script
The Nāgarī script or Northern Nagari of Kashi is the ancestor of Devanagari
Devanagari ( ; , , Sanskrit pronunciation: ), also called Nagari (),Kathleen Kuiper (2010), The Culture of India, New York: The Rosen Publishing Group, , page ...

rotated the lines clockwise, so they appeared horizontally, and ended each line with a short downward stroke on the right. In cursive script, the three strokes were eventually connected to form a glyph resembling a with an additional stroke at the bottom: ३.
The Indian digits spread to the Caliphate
A caliphate or khilāfah ( ar, خِلَافَة, ) is an institution or public office under the leadership of an Islamic steward with the title of caliph (; ar, خَلِيفَة , ), a person considered a political-religious successor to th ...

in the 9th century. The bottom stroke was dropped around the 10th century in the western parts of the Caliphate, such as the Maghreb
The Maghreb (; ar, الْمَغْرِب, al-Maghrib, lit=the west), also known as the Arab Maghreb ( ar, المغرب العربي) and Northwest Africa, is the western part of North Africa and the Arab world. The region includes Algeria, ...

and Al-Andalus
Al-Andalus translit. ; an, al-Andalus; ast, al-Ándalus; eu, al-Andalus; ber, ⴰⵏⴷⴰⵍⵓⵙ, label=Berber, translit=Andalus; ca, al-Àndalus; gl, al-Andalus; oc, Al Andalús; pt, al-Ândalus; es, al-Ándalus () was the Mus ...

, when a distinct variant ("Western Arabic") of the digit symbols developed, including modern Western 3. In contrast, the Eastern Arabs retained and enlarged that stroke, rotating the digit once more to yield the modern ("Eastern") Arabic
Arabic (, ' ; , ' or ) is a Semitic languages, Semitic language spoken primarily across the Arab world.Semitic languages: an international handbook / edited by Stefan Weninger; in collaboration with Geoffrey Khan, Michael P. Streck, Janet C ...

digit "٣".
In most modern Western typeface
A typeface (or font family) is the design of lettering that can include variations in size, weight (e.g. bold), slope (e.g. italic), width (e.g. condensed), and so on. Each of these variations of the typeface is a font.
There are list of type ...

s, the digit 3, like the other decimal digit
A numerical digit (often shortened to just digit) is a single symbol used alone (such as "2") or in combinations (such as "25"), to represent numbers in a Positional notation, positional numeral system. The name "digit" comes from the fact that t ...

s, has the height of a capital letter
Letter case is the distinction between the letters that are in larger uppercase or capitals (or more formally ''majuscule'') and smaller lowercase (or more formally ''minuscule'') in the written representation of certain languages. The writi ...

, and sits on the baseline. In typefaces with text figures
Text figures (also known as non-lining, lowercase, old style, ranging, hanging, medieval, billing, or antique figures or numerals) are numerals designed with varying heights in a fashion that resembles a typical line of running text, hence the ...

, on the other hand, the glyph usually has the height of a lowercase letter
Letter case is the distinction between the Letter (alphabet), letters that are in larger uppercase or capitals (or more formally ''majuscule'') and smaller lowercase (or more formally ''minuscule'') in the written representation of certain lang ...

"x" and a descender
In typography and handwriting, a descender is the portion of a letter that extends below the baseline of a font.
For example, in the letter ''y'', the descender is the "tail", or that portion of the diagonal line which lies below the ''v'' ...

: "". In some French text-figure typefaces, though, it has an ascender instead of a descender.
A common graphic variant of the digit three has a flat top, similar to the letter Ʒ (ezh). This form is sometimes used to prevent falsifying a 3 as an 8. It is found on UPC-A barcodes and standard 52-card deck
The standard 52-card deck of French-suited playing cards is the most common pack of playing cards used today. In English-speaking countries it is the only traditional pack used for playing cards; in many countries of the world, however, it is used ...

s.
Mathematics

3 is the second smallestprime number
A prime number (or a prime) is a natural number greater than 1 that is not a product of two smaller natural numbers. A natural number greater than 1 that is not prime is called a composite number. For example, 5 is prime because the only wa ...

and the first odd
Odd means unpaired, occasional, strange or unusual, or a person who is viewed as eccentric.
Odd may also refer to:
Acronym
* ODD (Text Encoding Initiative) ("One Document Does it all"), an abstracted literate-programming format for describing ...

prime number. It is the first unique prime
The reciprocals of prime numbers have been of interest to mathematicians for various reasons. They Divergence of the sum of the reciprocals of the primes, do not have a finite sum, as Leonhard Euler proved in 1737.
Like all rational numbers, th ...

, such that the period length
A periodic function is a function that repeats its values at regular intervals. For example, the trigonometric functions
In mathematics
Mathematics is an area of knowledge that includes the topics of numbers, formulas and related s ...

value of 1 of the decimal expansion
A decimal representation of a non-negative real number is its expression as a sequence of symbols consisting of decimal digits traditionally written with a single separator:
r = b_k b_\ldots b_0.a_1a_2\ldots
Here is the decimal separator, is ...

of its reciprocal
Reciprocal may refer to:
In mathematics
* Multiplicative inverse
In mathematics, a multiplicative inverse or reciprocal for a number ''x'', denoted by 1/''x'' or ''x''−1, is a number which when Multiplication, multiplied by ''x'' yield ...

, 0.333..., is unique. 3 is a twin prime
A twin prime is a prime number that is either 2 less or 2 more than another prime number—for example, either member of the twin prime pair (41, 43). In other words, a twin prime is a prime that has a prime gap of two. Sometimes the term ''twin pr ...

with 5, and a cousin prime
In number theory
Number theory (or arithmetic or higher arithmetic in older usage) is a branch of pure mathematics devoted primarily to the study of the integer
An integer is the number zero (), a positive natural number (, , , etc.) o ...

with 7, and the only known number $n$ such that $n$! - 1 and $n$! + 1 are prime, as well as the only prime number $p$ such that $p$ - 1 yields another prime number, 2. A triangle
A triangle is a polygon with three Edge (geometry), edges and three Vertex (geometry), vertices. It is one of the basic shapes in geometry. A triangle with vertices ''A'', ''B'', and ''C'' is denoted \triangle ABC.
In Euclidean geometry, an ...

is made of three sides. It is the smallest non-self-intersecting polygon
In geometry, a polygon () is a plane figure that is described by a finite number of straight line segments connected to form a closed '' polygonal chain'' (or ''polygonal circuit''). The bounded plane region, the bounding circuit, or the tw ...

and the only polygon not to have proper diagonals
In geometry, a diagonal is a line segment joining two vertex (geometry), vertices of a polygon or polyhedron, when those vertices are not on the same edge (geometry), edge. Informally, any sloping line is called diagonal. The word ''diagonal'' ...

. When doing quick estimates, 3 is a rough approximation of , 3.1415..., and a very rough approximation of ''e'', 2.71828...
3 is the first Mersenne prime
In mathematics
Mathematics is an area of knowledge that includes the topics of numbers, formulas and related structures, shapes and the spaces in which they are contained, and quantities and their changes. These topics are represented in mo ...

, as well as the second Mersenne prime exponent and the second double Mersenne prime exponent, for 7 and 127, respectively. 3 is also the first of five known Fermat prime
In mathematics
Mathematics is an area of knowledge that includes the topics of numbers, formulas and related structures, shapes and the spaces in which they are contained, and quantities and their changes. These topics are represented in m ...

s, which include 5, 17, 257
__NOTOC__
Year 257 (Roman numerals, CCLVII) was a common year starting on Thursday (link will display the full calendar) of the Julian calendar. At the time, it was known as the Year of the Consulship of Valerianus and Gallienus (or, less freq ...

, and 65537. It is the second Fibonacci prime
A Fibonacci prime is a Fibonacci number
In mathematics, the Fibonacci numbers, commonly denoted , form a integer sequence, sequence, the Fibonacci sequence, in which each number is the sum of the two preceding ones. The sequence commonly start ...

(and the second Lucas prime
The Lucas numbers or Lucas series are an integer sequence named after the mathematician Édouard Lucas, François Édouard Anatole Lucas (1842–1891), who studied both that sequence and the closely related Fibonacci numbers. Lucas numbers a ...

), the second Sophie Germain prime
In number theory, a prime number ''p'' is a Sophie Germain prime if 2''p'' + 1 is also prime. The number 2''p'' + 1 associated with a Sophie Germain prime is called a safe prime. For example, 11 is a Sophie Germain prime and 2&t ...

, and the second factorial prime
A factorial prime is a prime number
A prime number (or a prime) is a natural number greater than 1 that is not a product of two smaller natural numbers. A natural number greater than 1 that is not prime is called a composite number. For ex ...

, as it is equal to 2! + 1.
3 is the second and only prime triangular number
A triangular number or triangle number counts objects arranged in an equilateral triangle. Triangular numbers are a type of figurate number, other examples being square numbers and Cube (algebra)#In integers, cube numbers. The th triangular numbe ...

, and Gauss
Johann Carl Friedrich Gauss (; german: Gauß ; la, Carolus Fridericus Gauss; 30 April 177723 February 1855) was a German mathematician and physicist who made significant contributions to many fields in mathematics and science. Sometimes refer ...

proved that every integer is the sum of at most 3 triangular numbers
A triangular number or triangle number counts objects arranged in an equilateral triangle. Triangular numbers are a type of figurate number, other examples being square numbers and Cube (algebra)#In integers, cube numbers. The th triangular numbe ...

.
3 is the number of non-collinear points needed to determine a plane
Plane(s) most often refers to:
* Aero- or airplane
An airplane or aeroplane (informally plane) is a fixed-wing aircraft that is propelled forward by thrust from a jet engine, Propeller (aircraft), propeller, or rocket engine. Airplanes co ...

and a circle
A circle is a shape consisting of all point (geometry), points in a plane (mathematics), plane that are at a given distance from a given point, the Centre (geometry), centre. Equivalently, it is the curve traced out by a point that moves in ...

.
Three is the only prime which is one less than a perfect square. Any other number which is $n^2$ − 1 for some integer $n$ is not prime, since it is ($n$ − 1)($n$ + 1). This is true for 3 as well (with $n$ = 2), but in this case the smaller factor is 1. If $n$ is greater than 2, both $n$ − 1 and $n$ + 1 are greater than 1 so their product is not prime.
A natural number
In mathematics, the natural numbers are those numbers used for counting (as in "there are ''six'' coins on the table") and ordering (as in "this is the ''third'' largest city in the country").
Numbers used for counting are called ''Cardinal n ...

is divisible
In mathematics, a divisor of an integer n, also called a factor of n, is an integer m that may be multiplied by some integer to produce n. In this case, one also says that n is a multiple of m. An integer n is divisible or evenly divisible by ...

by three if the sum of its digits in base 10
The decimal numeral system (also called the base-ten positional numeral system and denary or decanary) is the standard system for denoting integer and non-integer numbers. It is the extension to non-integer numbers of the Hindu–Arabic numeral ...

is divisible by 3. For example, the number 21 is divisible by three (3 times 7) and the sum of its digits is 2 + 1 = 3. Because of this, the reverse of any number that is divisible by three (or indeed, any permutation
In mathematics, a permutation of a Set (mathematics), set is, loosely speaking, an arrangement of its members into a sequence or linear order, or if the set is already ordered, a rearrangement of its elements. The word "permutation" also refers ...

of its digits) is also divisible by three. For instance, 1368 and its reverse 8631 are both divisible by three (and so are 1386, 3168, 3186, 3618, etc.). See also Divisibility rule
A divisibility rule is a shorthand and useful way of determining whether a given integer
An integer is the number zero (), a positive natural number (, , , etc.) or a negative integer with a minus sign (−1, −2, −3, etc.). The negative n ...

. This works in base 10
The decimal numeral system (also called the base-ten positional numeral system and denary or decanary) is the standard system for denoting integer and non-integer numbers. It is the extension to non-integer numbers of the Hindu–Arabic numeral ...

and in any positional numeral system
Positional notation (or place-value notation, or positional numeral system) usually denotes the extension to any radix, base of the Hindu–Arabic numeral system (or decimal, decimal system). More generally, a positional system is a numeral syste ...

whose base divided by three leaves a remainder of one (bases 4, 7, 10, etc.).
Three of the five Platonic solids
In geometry, a Platonic solid is a Convex polytope, convex, regular polyhedron in three-dimensional space, three-dimensional Euclidean space. Being a regular polyhedron means that the face (geometry), faces are congruence (geometry), congruent (id ...

have triangular faces – the tetrahedron
In geometry, a tetrahedron (plural: tetrahedra or tetrahedrons), also known as a triangular Pyramid (geometry), pyramid, is a polyhedron composed of four triangular Face (geometry), faces, six straight Edge (geometry), edges, and four vertex ( ...

, the octahedron
In geometry
Geometry (; ) is, with arithmetic, one of the oldest branches of mathematics. It is concerned with properties of space such as the distance, shape, size, and relative position of figures. A mathematician who works in the field ...

, and the icosahedron
In geometry, an icosahedron ( or ) is a polyhedron with 20 faces. The name comes and . The plural can be either "icosahedra" () or "icosahedrons".
There are infinitely many non-similarity (geometry), similar shapes of icosahedra, some of them ...

. Also, three of the five Platonic solids have vertices where three faces meet – the tetrahedron
In geometry, a tetrahedron (plural: tetrahedra or tetrahedrons), also known as a triangular Pyramid (geometry), pyramid, is a polyhedron composed of four triangular Face (geometry), faces, six straight Edge (geometry), edges, and four vertex ( ...

, the hexahedron
A hexahedron (plural: hexahedra or hexahedrons) or sexahedron (plural: sexahedra or sexahedrons) is any polyhedron
In geometry, a polyhedron (plural polyhedra or polyhedrons; ) is a Three-dimensional space, three-dimensional shape with flat po ...

(cube
In geometry, a cube is a three-dimensional space, three-dimensional solid object bounded by six square (geometry), square faces, Facet (geometry), facets or sides, with three meeting at each vertex (geometry), vertex. Viewed from a corner it i ...

), and the dodecahedron
In geometry, a dodecahedron (Greek , from ''dōdeka'' "twelve" + ''hédra'' "base", "seat" or "face") or duodecahedron is any polyhedron with twelve flat faces. The most familiar dodecahedron is the regular dodecahedron with regular pentagon ...

. Furthermore, only three different types of polygons
In geometry, a polygon () is a plane (mathematics), plane Shape, figure that is described by a finite number of straight line segments connected to form a closed ''polygonal chain'' (or ''polygonal circuit''). The bounded plane region (mathemati ...

comprise the faces of the five Platonic solids – the triangle
A triangle is a polygon with three Edge (geometry), edges and three Vertex (geometry), vertices. It is one of the basic shapes in geometry. A triangle with vertices ''A'', ''B'', and ''C'' is denoted \triangle ABC.
In Euclidean geometry, an ...

, the square
In Euclidean geometry, a square is a regular polygon, regular quadrilateral, which means that it has four equal sides and four equal angles (90-degree (angle), degree angles, π/2 radian angles, or right angles). It can also be defined as a rec ...

, and the pentagon
In geometry, a pentagon (from the Greek language, Greek πέντε ''pente'' meaning ''five'' and γωνία ''gonia'' meaning ''angle'') is any five-sided polygon or 5-gon. The sum of the internal angles in a simple polygon, simple pentagon is ...

.
There are only three distinct 4×4 panmagic square A pandiagonal magic square or panmagic square (also diabolic square, diabolical square or diabolical magic square) is a magic square with the additional property that the broken diagonals, i.e. the diagonals that wrap round at the edges of the squar ...

s.
According to Pythagoras
Pythagoras of Samos ( grc, Πυθαγόρας ὁ Σάμιος, Pythagóras ho Sámios, Pythagoras the Samos, Samian, or simply ; in Ionian Greek; ) was an ancient Ionians, Ionian Ancient Greek philosophy, Greek philosopher and the eponymou ...

and the Pythagorean school, the number 3, which they called ''triad'', is the noblest of all digits, as it is the only number to equal the sum of all the terms below it, and the only number whose sum with those below equals the product of them and itself.
There are three finite convex uniform polytope groups in three dimensions, aside from the infinite families of prisms and antiprisms
In geometry, an antiprism or is a polyhedron composed of two Parallel (geometry), parallel Euclidean group, direct copies (not mirror images) of an polygon, connected by an alternating band of triangles. They are represented by the Conway po ...

: the tetrahedral group, the octahedral group, and the icosahedral group
In mathematics, and especially in geometry, an object has icosahedral symmetry if it has the same symmetries
Symmetry (from grc, συμμετρία "agreement in dimensions, due proportion, arrangement") in everyday language refers ...

. In dimensions $n$ ⩾ 5, there are only three regular polytopes: the $n$-simplex
In geometry
Geometry (; ) is, with arithmetic, one of the oldest branches of mathematics. It is concerned with properties of space such as the distance, shape, size, and relative position of figures. A mathematician who works in the field of ...

es, $n$-cube
In geometry, a cube is a three-dimensional space, three-dimensional solid object bounded by six square (geometry), square faces, Facet (geometry), facets or sides, with three meeting at each vertex (geometry), vertex. Viewed from a corner it i ...

s, and $n$-orthoplex
In geometry, a cross-polytope, hyperoctahedron, orthoplex, or cocube is a regular polytope, regular, convex polytope that exists in ''n''-dimensions, dimensional Euclidean space. A 2-dimensional cross-polytope is a square, a 3-dimensional cross-p ...

es. In dimensions $n$ ⩾ 9, the only three uniform polytope families, aside from the numerous infinite proprism
In geometry of 4 dimensions or higher, a proprism is a polytope resulting from the Cartesian product of two or more polytopes, each of two dimensions or higher. The term was coined by John Horton Conway for ''product prism''. The dimension of the s ...

atic families, are the $\backslash mathrm\_$ simplex, $\backslash mathrm\_$ cubic, and $\backslash mathrm\_$ demihypercubic families. For paracompact hyperbolic honeycombs, there are three groups in dimension
In physics and mathematics, the dimension of a Space (mathematics), mathematical space (or object) is informally defined as the minimum number of coordinates needed to specify any Point (geometry), point within it. Thus, a Line (geometry), lin ...

s 6 and 9, or equivalently of ranks 7 and 10, with no other forms in higher dimensions. Of the final three groups, the largest and most important is $\_9$, that is associated with an important Kac–Moody Lie algebra
In mathematics, a Lie algebra (pronounced ) is a vector space \mathfrak g together with an Binary operation, operation called the Lie bracket, an Alternating multilinear map, alternating bilinear map \mathfrak g \times \mathfrak g \rightarrow ...

$\backslash mathrm\; \_$.
The trisection of the angle was one of the three famous problems of antiquity.
Numeral systems

There is some evidence to suggest that early man may have used counting systems which consisted of "One, Two, Three" and thereafter "Many" to describe counting limits. Early peoples had a word to describe the quantities of one, two, and three but any quantity beyond was simply denoted as "Many". This is most likely based on the prevalence of this phenomenon among people in such disparate regions as the deep Amazon and Borneo jungles, where western civilization's explorers have historical records of their first encounters with these indigenous people.List of basic calculations

Science

*The Roman numeral III stands forgiant star
A giant star is a star with substantially larger radius and luminosity than a main sequence, main-sequence (or ''dwarf'') star of the same effective temperature, surface temperature.Giant star, entry in ''Astronomy Encyclopedia'', ed. Patrick Moo ...

in the Yerkes spectral classification scheme.
*Three is the atomic number
The atomic number or nuclear charge number (symbol ''Z'') of a chemical element is the charge number of an atomic nucleus. For ordinary nuclei, this is equal to the proton number (''n''p) or the number of protons found in the nucleus of every ...

of lithium
Lithium (from el, λίθος, lithos, lit=stone) is a chemical element with the Symbol (chemistry), symbol Li and atomic number 3. It is a soft, silvery-white alkali metal. Under standard temperature and pressure, standard conditions, it ...

.
*Three is the ASCII
ASCII ( ), abbreviated from American Standard Code for Information Interchange, is a character encoding standard for electronic communication. ASCII codes represent text in computers, telecommunications equipment, and other devices. Because of ...

code of "End of Text
The End-of-Text character (ETX) is a control character used to inform the receiving computer that the end of a record has been reached. This may or may not be an indication that all of the data in a record have been received. In ASCII and in EBCD ...

".
*Three is the number of dimensions
In physics and mathematics, the dimension of a Space (mathematics), mathematical space (or object) is informally defined as the minimum number of coordinates needed to specify any Point (geometry), point within it. Thus, a Line (geometry), lin ...

that humans can perceive. Humans perceive the universe
The universe is all of space and time and their contents, including planets, stars, galaxy, galaxies, and all other forms of matter and energy. The Big Bang theory is the prevailing cosmology, cosmological description of the development of ...

to have three spatial dimensions, but some theories, such as string theory
In physics, string theory is a Mathematical theory, theoretical framework in which the Point particle, point-like particles of particle physics are replaced by Dimension (mathematics and physics), one-dimensional objects called String (physic ...

, suggest there are more.
*Three is the number of elementary fermion generations according to the Standard Model
The Standard Model of particle physics
Particle physics or high energy physics is the study of Elementary particle, fundamental particles and fundamental interaction, forces that constitute matter and radiation. The fundamental particles ...

of particle physics.
*The triangle
A triangle is a polygon with three Edge (geometry), edges and three Vertex (geometry), vertices. It is one of the basic shapes in geometry. A triangle with vertices ''A'', ''B'', and ''C'' is denoted \triangle ABC.
In Euclidean geometry, an ...

, a polygon
In geometry, a polygon () is a plane figure that is described by a finite number of straight line segments connected to form a closed '' polygonal chain'' (or ''polygonal circuit''). The bounded plane region, the bounding circuit, or the tw ...

with three edges and three vertices, is the most stable physical shape. For this reason it is widely utilized in construction, engineering and design.
*The ability of the human eye
The human eye is a sensory organ (biology), organ, part of the sensory nervous system, that reacts to light, visible light and allows humans to use visual information for various purposes including Visual perception, seeing things, Balance (abil ...

to distinguish color
Color (American English) or colour (British English) is the visual perception, visual perceptual Physical property, property deriving from the spectrum of light interacting with the photoreceptor cells of the eyes. Color categories and physica ...

s is based upon the varying sensitivity of different cells in the retina
The retina (from la, rete "net") is the innermost, light-sensitive layer of tissue of the eye of most vertebrates and some molluscs
Mollusca is the second-largest phylum of invertebrate animals after the Arthropoda, the members of whi ...

to light of different wavelengths
In physics, the wavelength is the spatial period of a periodic wave—the distance over which the wave's shape repeats.
It is the distance between consecutive corresponding points of the same phase (waves), phase on the wave, such as two adjac ...

. Humans being trichromatic
Trichromacy or trichromatism is the possessing of three independent channels for conveying color information, derived from the three different types of cone cells in the eye. Organisms with trichromacy are called trichromats.
The normal expla ...

, the retina contains three types of color receptor cells, or cones
A cone is a three-dimensional space, three-dimensional geometric shape that tapers smoothly from a flat base (frequently, though not necessarily, circular) to a point called the Apex (geometry), apex or vertex (geometry), vertex.
A cone is ...

.
*There are three primary color
A set of primary colors or primary colours (see spelling differences) consists of colorants or colored lights that can be mixed in varying amounts to produce a gamut of colors. This is the essential method used to create the perception of ...

s in the additive
Additive may refer to:
Mathematics
* Additive function, a function in number theory
* Additive map, a function that preserves the addition operation
* Additive set-functionn see Sigma additivity
* Additive category, a preadditive category with fi ...

and subtractive models.
Protoscience

*In Europeanalchemy
Alchemy (from Arabic: ''al-kīmiyā''; from Ancient Greek: χυμεία, ''khumeía'') is an ancient branch of natural philosophy, a philosophical and protoscience, protoscientific tradition that was historically practiced in Chinese alchemy, C ...

, the three primes ( la, tria prima) were salt
Salt is a mineral composed primarily of sodium chloride (NaCl), a chemical compound belonging to the larger class of Salt (chemistry), salts; salt in the form of a natural crystallinity, crystalline mineral is known as rock salt or halite. ...

(), sulfur
Sulfur (or sulphur in British English
British English (BrE, en-GB, or BE) is, according to Oxford Dictionaries, " English as used in Great Britain, as distinct from that used elsewhere". More narrowly, it can refer specifically to the ...

() and mercury ().Eric John Holmyard. ''Alchemy.'' 1995. p.153
*The three doshas (weaknesses) and their antidote
An antidote is a substance that can counteract a form of poisoning. The term ultimately derives from the Greek term φάρμακον ἀντίδοτον ''(pharmakon) antidoton'', "(medicine) given as a remedy". Antidotes for anticoagulants are s ...

s are the basis of Ayurvedic medicine
Ayurveda () is an alternative medicine
Alternative medicine is any practice that aims to achieve the healing effects of medicine despite lacking biological plausibility, testability, repeatability, or evidence from clinical trials. Complem ...

in India.
Pseudoscience

*Three is the symbolic representation for Mu,Augustus Le Plongeon
Augustus Henry Julian Le Plongeon (4 May 1825 – 13 December 1908) was a British-American archeologist and photographer who studied the pre-Columbian
In the history of the Americas, the pre-Columbian era spans from the Migration to the New W ...

's and James Churchward's lost continent.
*In Pythagorean numerology
Numerology (also known as arithmancy) is the belief in an occult, divine or mystical relationship between a number
A number is a mathematical object used to count, measure, and label. The original examples are the natural numbers 1 ...

the number 3 is the digit that represents the communication. It encourages the expansion of creativity, sociability between people and movement. For Pythagoras, the number 3 was a perfect number, representing harmony, perfection, and divine proportion.
Philosophy

*Philosophers such asAquinas
Thomas Aquinas, Dominican Order, OP (; it, Tommaso d'Aquino, lit=Thomas of Aquino, Italy, Aquino; 1225 – 7 March 1274) was an Italian Dominican Order, Dominican friar and Catholic priest, priest who was an influential List of Catholic philo ...

, Kant
Immanuel Kant (, , ; 22 April 1724 – 12 February 1804) was a German Philosophy, philosopher and one of the central Age of Enlightenment, Enlightenment thinkers. Born in Königsberg, Kant's comprehensive and systematic works in epistemolo ...

, Hegel
Georg Wilhelm Friedrich Hegel (; ; 27 August 1770 – 14 November 1831) was a German philosopher. He is one of the most important figures in German idealism and one of the founding figures of 19th century philosophy, modern Western philosophy. ...

, C. S. Peirce, and Karl Popper
Sir Karl Raimund Popper (28 July 1902 – 17 September 1994) was an Austrian-British philosopher, academic and social commentator. One of the 20th century's most influential philosophers of science, Popper is known for his rejection of the cl ...

have made threefold divisions, or '' trichotomies'', which have been important in their work.
*Hegel
Georg Wilhelm Friedrich Hegel (; ; 27 August 1770 – 14 November 1831) was a German philosopher. He is one of the most important figures in German idealism and one of the founding figures of 19th century philosophy, modern Western philosophy. ...

's dialectic
Dialectic ( grc-gre, διαλεκτική, ''dialektikḗ''; related to dialogue; german: Dialektik), also known as the dialectical method, is a discourse between two or more people holding different points of view about a subject but wishing ...

of Thesis + Antithesis = Synthesis creates three-ness from two-ness.
Religion

Many world religions contain triple deities or concepts of trinity, including: *TheHindu
Hindus (; ) are people who religiously adhere to Hinduism.Jeffery D. Long (2007), A Vision for Hinduism, IB Tauris, , pages 35–37 Historically, the term has also been used as a geographical, cultural, and later religious identifier for ...

Trimurti
The Trimūrti (; Sanskrit: त्रिमूर्ति ', "three forms" or "trinity") are the triple deity, trinity of Para Brahman, supreme divinity in Hinduism, in which the cosmic functions of creation ex nihilo, creation, Conservation ...

*The Hindu Tridevi
The Tridevi () are a trinity of Para Brahman, supreme divinity in Hinduism, joining a Triad (religious), triad of eminent goddesses either as a feminine version of the Trimurti, or as consorts of a masculine Trimurti, depending on the denominati ...

*The Three Jewels
In Buddhism, refuge or taking refuge refers to a religious practice, which often includes a prayer or recitation performed at the beginning of the day or of a practice session. Since the period of Early Buddhist schools, Early Buddhism until pre ...

of Buddhism
Buddhism ( , ), also known as Buddha Dharma and Dharmavinaya (), is an Indian religions, Indian religion or Indian philosophy#Buddhist philosophy, philosophical tradition based on Pre-sectarian Buddhism, teachings attributed to the Buddha. ...

*The Three Pure Ones
The Three Pure Ones (), also translated as the Three Pure Pellucid Ones, the Three Pristine Ones, the Three Divine Teachers, the Three Clarities, or the Three Purities, are the three highest gods in the Taoist
Taoism (, ) or Daoism () ref ...

of Taoism
Taoism (, ) or Daoism () refers to either a school of Philosophy, philosophical thought (道家; ''daojia'') or to a religion (道教; ''daojiao''), both of which share ideas and concepts of China, Chinese origin and emphasize living in harmo ...

*The Christian
Christians () are people who follow or adhere to Christianity
Christianity is an Abrahamic religions, Abrahamic Monotheism, monotheistic religion based on the Life of Jesus in the New Testament, life and Teachings of Jesus, teachings of ...

Holy Trinity
The Christian theology, Christian doctrine of the Trinity (, from 'threefold') is the central dogma concerning the nature of God in most Christian churches, which defines Monotheism, one God existing in three wikt:coequal, coequal, wikt:coe ...

*The Triple Goddess of Wicca
Wicca () is a Modern Paganism, modern Pagan religion. Religious studies, Scholars of religion categorise it as both a new religious movement and as part of the occultism, occultist stream of Western esotericism. It was developed in England duri ...

Christianity

*The threefold office ofChrist
Jesus, likely from he, יֵשׁוּעַ, translit=Yēšūaʿ, label=Hebrew/Aramaic ( AD 30 or 33), also referred to as Jesus Christ or Jesus of Nazareth (among other Names and titles of Jesus in the New Testament, names and titles), was ...

is a Christian doctrine which states that Christ performs the functions of prophet
In religion, a prophet or prophetess is an individual who is regarded as being in contact with a divinity, divine being and is said to speak on behalf of that being, serving as an intermediary with humanity by delivering messages or teachings f ...

, priest
A priest is a religious leader authorized to perform the sacred rituals of a religion, especially as a mediatory agent between humans and one or more deity, deities. They also have the authority or power to administer religious rites; in p ...

, and king
King is the title given to a male monarch in a variety of contexts. The female equivalent is queen regnant, queen, which title is also given to the queen consort, consort of a king.
*In the context of prehistory, antiquity and contempora ...

.
*The ministry of Jesus
The ministry of Jesus, in the canonical gospels, begins with Baptism of Jesus, his baptism in the countryside of Roman Judea and Transjordan (Bible), Transjordan, near the River Jordan by John the Baptist, and ends in Jerusalem in Christianity ...

lasted approximately three years.
*During the Agony in the Garden
The Agony in the Garden of Gethsemane is an episode in the life of Jesus
Jesus, likely from he, יֵשׁוּעַ, translit=Yēšūaʿ, label=Hebrew/Aramaic ( AD 30 or 33), also referred to as Jesus Christ or Jesus of Nazareth (amon ...

, Christ asked three times for the cup to be taken from him.
*Jesus rose from the dead on the third day after his death.
*The devil tempted Jesus three times.
*Saint Peter
Saint Peter; he, שמעון בר יונה, Šimʿōn bar Yōnāh; ar, سِمعَان بُطرُس, translit=Simʿa̅n Buṭrus; grc-gre, Πέτρος, Petros; cop, Ⲡⲉⲧⲣⲟⲥ, Petros; lat, Petrus; ar, شمعون الصفـا, Sham'un ...

thrice denied Jesus and thrice affirmed his faith in Jesus.
*The Magi
Magi (; singular magus ; from Latin ''wikt:magus#Noun 2, magus'', cf. fa, مغ ) were priests in Zoroastrianism and the earlier religions of the Western Iranian languages, western Iranians. The earliest known use of the word ''magi'' is in the ...

– wise men who were astronomers/astrologers from Persia – gave Jesus three gifts.
*There are three Synoptic Gospels
The gospels of Gospel of Matthew, Matthew, Gospel of Mark, Mark, and Gospel of Luke, Luke are referred to as the synoptic Gospels because they include many of the same stories, often in a similar sequence and in similar or sometimes identical ...

and three epistles of John.
*Paul the Apostle
Paul; grc, Παῦλος, translit=Paulos; cop, ⲡⲁⲩⲗⲟⲥ; hbo, פאולוס השליח (previously called Saul of Tarsus;; ar, بولس الطرسوسي; grc, Σαῦλος Ταρσεύς, Saũlos Tarseús; tr, Tarsuslu Pavlus; ...

went blind for three days after his conversion to Christianity
Conversion to Christianity is the religious conversion of a previously non-Christian person to Christianity. Different Christian denominations may perform various different kinds of rituals or ceremonies initiation into their community of believe ...

.
Judaism

*Noah
Noah ''Nukh''; am, ኖህ, ''Noḥ''; ar, نُوح '; grc, Νῶε ''Nôe'' () is the tenth and last of the pre-Flood patriarchs in the traditions of Abrahamic religions
The Abrahamic religions are a group of religions centered aroun ...

had three sons: Ham
Ham is pork
Pork is the culinary name for the meat of the Pig, domestic pig (''Sus domesticus''). It is the most commonly consumed meat worldwide, with evidence of pig animal husbandry, husbandry dating back to 5000 BCE.
Pork is ...

, Shem
Shem (; he, שֵׁם ''Šēm''; ar, سَام, Sām) ''Sḗm''; Ge'ez language, Ge'ez: ሴም, ''Sēm'' was one of the sons of Noah in the book of Genesis and in the book of Chronicles, and the Quran.
The children of Shem were Elam (Hebrew ...

and Japheth
Japheth ( he, יֶפֶת ''Yép̄eṯ'', in pausa ''Yā́p̄eṯ''; el, Ἰάφεθ '; la, Iafeth, Iapheth, Iaphethus, Iapetus) is one of the three sons of Noah in the Book of Genesis, in which he plays a role in the story of Noah's drunkenn ...

*The Three Patriarchs
The highest-ranking bishops in Eastern Orthodoxy, Oriental Orthodoxy, the Catholic Church (above major archbishop and primate (bishop), primate), the Hussite Church, Church of the East, and some Independent Catholicism, Independent Catholic Chur ...

: Abraham
Abraham, ; ar, , , name=, group= (originally Abram) is the common Hebrews, Hebrew patriarch of the Abrahamic religions, including Judaism, Christianity, and Islam. In Judaism, he is the founding father of the Covenant (biblical), special ...

, Isaac
Isaac; grc, Ἰσαάκ, Isaák; ar, إسحٰق/إسحاق, Isḥāq; am, ይስሐቅ is one of the three patriarchs (Bible), patriarchs of the Israelites and an important figure in the Abrahamic religions, including Judaism, Christianity, a ...

and Jacob
Jacob (; ; ar, يَعْقُوب, Jacob in Islam, Yaʿqūb; gr, Ἰακώβ, Iakṓb), later given the name Israel (name), Israel, is regarded as a Patriarchs (Bible), patriarch of the Israelites and is an important figure in Abrahamic religi ...

*The prophet Balaam
Balaam (; , Hebrew language#Modern Hebrew, Standard ''Bīlʿam'' Tiberian vocalization, Tiberian ''Bīlʿām'') is a divination, diviner in the Torah (Pentateuch) whose story begins in Chapter 22 of the Book of Numbers (). Ancient references to B ...

beat his donkey three times.
*The prophet Jonah
Jonah or Jonas, ''Yōnā'', "dove"; gr, Ἰωνᾶς ''Iōnâs''; ar, يونس ' or '; Latin: ''Ionas'' Ben (Hebrew), son of Amittai, is a prophet in the Hebrew Bible and the Quran, from Gath-hepher of the northern Kingdom of Israel (Samaria ...

spent three days and nights in the belly of a large fish
*Three divisions of the Written Torah
The Torah (; hbo, ''Tōrā'', "Instruction", "Teaching" or "Law") is the compilation of the first five books of the Hebrew Bible, namely the books of Book of Genesis, Genesis, Book of Exodus, Exodus, Leviticus, Book of Numbers, Numbers a ...

: Torah
The Torah (; hbo, ''Tōrā'', "Instruction", "Teaching" or "Law") is the compilation of the first five books of the Hebrew Bible, namely the books of Book of Genesis, Genesis, Book of Exodus, Exodus, Leviticus, Book of Numbers, Numbers a ...

(Five Books of Moses), Nevi'im
Nevi'im (; he, נְבִיאִים ''Nəvīʾīm'', Tiberian: ''Năḇīʾīm,'' "Prophets", literally "spokespersons") is the second major division of the Hebrew Bible
The Hebrew Bible or Tanakh (;

(Prophets), Ketuvim
The Ketuvim (; hbo, , Modern Hebrew, Modern: ''Kəṯūvīm'', Tiberian Hebrew, Tiberian: ''Kăṯūḇīm'' "writings") is the third and final section of the Tanakh (Hebrew Bible), after Torah (instruction) and Nevi'im (prophets). In English ...

(Writings)
*Three divisions of the Jewish people: Kohen
Kohen ( he, , ''kōhēn'', , "priest", pl. , ''kōhănīm'', , "priests") is the Hebrew word for "priest", used in reference to the Aaronic Priest#Judaism, priesthood, also called Aaronites or Aaronides. Levite, Levitical priests or ''kohanim' ...

, Levite
Levites (or Levi) (, he, ''Lǝvīyyīm'') are Jewish males who claim patrilineal descent from the Tribe of Levi. The Tribe of Levi descended from Levi, the third son of Jacob and Leah. The surname ''Halevi'', which consists of the Hebre ...

, Yisrael
*Three daily prayers
Prayer is an invocation
An invocation (from the Latin verbs, Latin verb ''invocare'' "to call on, invoke, to give") may take the form of:
*Supplication, prayer or Spell (paranormal), spell.
*A form of Spirit possession, possession.
*wik ...

: ''Shacharit
''Shacharit'' ( he, שַחֲרִית ''šaḥăriṯ''), or ''Shacharis'' in Ashkenazi Hebrew, is the morning ''Jewish prayer, tefillah'' (prayer) of Judaism, one of the three daily prayers.
Different traditions identify different primar ...

'', ''Mincha
Mincha ( he, מִנחַה, pronounced as ; sometimes spelled ''Minchah'' or ''Minḥa'') is the afternoon prayer service in Judaism.
Etymology
The name ''Mincha'', meaning "present", is derived from the meal offering that accompanied each sacrif ...

'', ''Maariv
''Maariv'' or ''Maʿariv'' (, ), also known as ''Arvit'' (, ), is a Jewish prayer service held in the evening or night
Night (also described as night time, unconventionally spelled as "nite") is the period of :wikt:ambient, ambient da ...

''
*Three Shabbat
Shabbat (, , or ; he, שַׁבָּת, Šabbāṯ, , ) or the Sabbath (), also called Shabbos (, ) by Ashkenazi Hebrew, Ashkenazim, is Judaism's day of rest on the seventh day of the seven-day week, week—i.e., Saturday. On this day, religious ...

meals
*Shabbat ends when three stars are visible in the night sky
*Three Pilgrimage Festivals
The Three Pilgrimage Festivals, in Hebrew ''Shalosh Regalim'' (שלוש רגלים), are three major festivals in Judaism—Pesach (''Passover''), Shavuot (''Weeks'' or ''Pentecost''), and Sukkot (''Tabernacles'', ''Tents'' or ''Booths'')—when a ...

: Passover
Passover, also called Pesach (; ), is a major Jewish holidays, Jewish holiday that celebrates the The Exodus, Biblical story of the Israelites escape from slavery in Ancient Egypt, Egypt, which occurs on the 15th day of the Hebrew calendar, He ...

, Shavuot
''Shavuot'' (), or ''Shavuos'' () in some Ashkenazi Jews, Ashkenazi usage ( he, , ''Šāvūʿōṯ'', "Weeks"), commonly known in English as the Feast of Weeks, is a Jewish holiday that occurs on the sixth day of the Hebrew month of Sivan (in ...

, Sukkot
or ("Booths, Tabernacles")
, observedby = Jews, Samaritans
Samaritans (; ; he, שומרונים, translit=Šōmrōnīm, lit=; ar, السامريون, translit=as-Sāmiriyyūn) are an ethnoreligious group who originate from the anc ...

*Three matzo
Matzah or matzo ( he, מַצָּה, translit=maṣṣā'','' pl. matzot or Ashkenazi Hebrew, Ashk. matzos) is an Unleavened bread, unleavened flatbread that is part of Jewish cuisine and forms an integral element of the Passover festival, dur ...

s on the Passover Seder
The Passover Seder (; he, סדר פסח , 'Passover order/arrangement'; yi, סדר ) is a ritual feast at the beginning of the Jewish holiday
Jewish holidays, also known as Jewish festivals or ''Yamim Tovim'' ( he, ימים טובים, ...

table
*The Three Weeks
The Three Weeks or ''Bein ha-Metzarim'' (Hebrew
Hebrew (; ; ) is a Northwest Semitic languages, Northwest Semitic language of the Afroasiatic languages, Afroasiatic language family. Historically, it is one of the spoken languages of the Is ...

, a period of mourning bridging the fast days of Seventeenth of Tammuz
, observedby = Jews
, date = 17th day of Tammuz
, observances = Fasting
Fasting is the abstention from eating and sometimes drinking. From a purely physiology, physiological context, "fasting" may refer to the metabolism, metabolic status o ...

and Tisha B'Av
Tisha B'Av ( he, תִּשְׁעָה בְּאָב ''Tīšʿā Bəʾāv''; , ) is an annual Ta'anit, fast day in Judaism, on which a number of disasters in Jewish history occurred, primarily the destruction of both Solomon's Temple by the Neo-Baby ...

*Three cardinal sins for which a Jew must die rather than transgress: idolatry
Idolatry is the worship of a cult image or "idol" as though it were God. In Abrahamic religions (namely Judaism, Samaritanism, Christianity, the Baháʼí Faith, and Islam) idolatry connotes the worship of something or someone other than the Go ...

, murder
Murder is the unlawful killing of another human
Humans (''Homo sapiens'') are the most abundant and widespread species of primate, characterized by bipedality, bipedalism and exceptional cognitive skills due to a large and complex Huma ...

, sexual immorality
Immorality is the violation of moral
A moral (from Latin ''morālis'') is a message that is conveyed or a lesson to be learned from a narrative, story or wikt:event, event. The moral may be left to the hearer, reader, or viewer to determine f ...

*Upsherin
Upsherin, Upsheren, Opsherin or Upsherinish (Yiddish: אפשערן, lit. "shear off", Judeo-Arabic languages, Judaeo-Arabic: חלאקה, ''ḥalāqah'') is a First haircut, haircutting ceremony observed by a wide cross-section of Jews and is p ...

, a Jewish boy's first haircut at age 3
*A Beth din
A beit din ( he, בית דין, Bet Din, house of judgment, , Ashkenazic: ''beis din'', plural: batei din) is a rabbinical court
A court is any person or institution, often as a government institution, with the authority to Adjudication, ad ...

is composed of three members
*Potential converts are traditionally turned away three times to test their sincerity
*In the Jewish mystical tradition of the Kabbalah
Kabbalah ( he, קַבָּלָה ''Qabbālā'', literally "reception, tradition") is an esoteric method, discipline and Jewish theology, school of thought in Jewish mysticism. A traditional Kabbalist is called a Mekubbal ( ''Məqūbbāl'' "rece ...

, it is believed that the soul
In many religious and philosophical traditions, there is a belief that a soul is "the immaterial aspect or essence
Essence ( la, essentia) is a polysemic term, used in philosophy and theology as a designation for the property (philosophy), ...

consists of three parts, with the highest being '' neshamah'' ("breath"), the middle being '' ruach'' ("wind" or "spirit") and the lowest being '' nefesh'' ("repose"). Sometimes the two elements of ''Chayah'' ("life" or "animal") and ''Yechidah'' ("unit") are additionally mentioned.
*In the Kabbalah, the Tree of Life
The tree of life is a fundamental archetype in many of the world's mythology, mythological, religion, religious, and philosophy, philosophical traditions. It is closely related to the concept of the sacred tree.Giovino, Mariana (2007). ''The ...

(Hebrew: ''Etz ha-Chayim'', עץ החיים) refers to a latter 3-pillar diagrammatic representation of its central mystical symbol, known as the '' 10 Sephirot''.
Islam

*The three core principles in Shia tradition: Tawhid (Oneness of God), Nabuwwa (Concept of Prophethood), Imama (Concept of Imam)Buddhism

*The TripleBodhi
The English term enlightenment is the Western translation of various Buddhist
Buddhism ( , ), also known as Buddha Dharma and Dharmavinaya (), is an Indian religion or philosophical tradition based on teachings attributed to the ...

(ways to understand the end of birth) are Budhu, Pasebudhu, and Mahaarahath.
*The Three Jewels
In Buddhism, refuge or taking refuge refers to a religious practice, which often includes a prayer or recitation performed at the beginning of the day or of a practice session. Since the period of Early Buddhist schools, Early Buddhism until pre ...

, the three things that Buddhists take refuge in.
Shinto

*TheImperial Regalia of Japan
The are the imperial regalia of Japan and consist of the sword , the mirror , and the jewel . They represent the three primary virtues: Courage, valour (the sword), wisdom (the mirror), and Altruism, benevolence (the jewel).Three Treasures (), the basic

^{1}) is considered a good number in ^{1}), compared to four (, pinyin: ''sì'', Cantonese: ''sei''^{1}), which sounds like the word "death" ( pinyin ''sǐ'', Cantonese: ''sei''^{2}).
Counting to three is common in situations where a group of people wish to perform an action in synchrony: ''Now, on the count of three, everybody pull!'' Assuming the counter is proceeding at a uniform rate, the first two counts are necessary to establish the rate, and the count of "three" is predicted based on the timing of the "one" and "two" before it. Three is likely used instead of some other number because it requires the minimal amount counts while setting a rate.
There is another superstition that it is unlucky to take a third light, that is, to be the third person to light a cigarette from the same match or lighter. This superstition is sometimes asserted to have originated among soldiers in the trenches of the First World War when a sniper might see the first light, take aim on the second and fire on the third.
The phrase " Third time's the charm" refers to the superstition that after two failures in any endeavor, a third attempt is more likely to succeed. This is also sometimes seen in reverse, as in "third man o do something, presumably forbiddengets caught".

bad

in the ''Oxford Dictionary of Phrase and Fable'', 2006, via Encyclopedia.com.

Tricyclopedic Book of Threes

by Michael Eck

by Dr. John A. McNulty *

The Number 3

The Positive Integer 3

{{DEFAULTSORT:3 (Number) Integers

virtues
Virtue ( la, virtus) is morality, moral excellence. A virtue is a trait or quality that is deemed to be morally good and thus is Value (ethics), valued as a foundation of principle and good moral being. In other words, it is a behavior that sh ...

in Taoism
Taoism (, ) or Daoism () refers to either a school of Philosophy, philosophical thought (道家; ''daojia'') or to a religion (道教; ''daojiao''), both of which share ideas and concepts of China, Chinese origin and emphasize living in harmo ...

.
*The Three Dantian
Dantian, dan t'ian, dan tien or tan t'ien is loosely translated as "elixir field", "sea of qi", or simply "energy center". Dantian are the "qi focus flow centers", important focal points for meditative and exercise techniques such as qigong, Ch ...

s
*Three Lines of a Trigram
Trigrams are a special case of the ''n''-gram, where ''n'' is 3. They are often used in natural language processing
Natural language processing (NLP) is an interdisciplinary subfield of linguistics, computer science, and artificial intellige ...

* Three Sovereigns: Heaven Fu Xi
Fuxi or Fu Hsi (伏羲 ~ 伏犧 ~ 伏戲) is a culture hero in Chinese legend and Chinese mythology, mythology, credited along with his sister and wife Nüwa with List of protoplasts, creating humanity and the invention of music, hunting, fishin ...

(Hand – Head – 3º Eye), Humanity Shen Nong
Shennong (), variously translated as "Divine Farmer" or "Divine Husbandman", born Jiang Shinian (), was a mythological Chinese ruler known as the first Yan Emperor
The Yan Emperor () or the Flame Emperor was a legendary ancient Chinese r ...

( Unit 69), Hell Nüwa
Nüwa, also read Nügua, is the mother goddess
A mother goddess is a goddess who represents a personified deification of motherhood, fertility goddess, fertility, Creation myth, creation, natural disasters, destruction, or the earth godde ...

(Foot – Abdomen – Umbiculus).
Hinduism

*TheTrimurti
The Trimūrti (; Sanskrit: त्रिमूर्ति ', "three forms" or "trinity") are the triple deity, trinity of Para Brahman, supreme divinity in Hinduism, in which the cosmic functions of creation ex nihilo, creation, Conservation ...

: Brahma
Brahma ( sa, ब्रह्मा, Brahmā) is a Hindu god, referred to as "the Creator" within the Trimurti, the triple deity, trinity of Para Brahman, supreme divinity that includes Vishnu, and Shiva.Jan Gonda (1969)The Hindu Trinity Anthro ...

the Creator, Vishnu
Vishnu ( ; , ), also known as Narayana and Hari, is one of the Hindu deities, principal deities of Hinduism. He is the supreme being within Vaishnavism, one of the major traditions within contemporary Hinduism.
Vishnu is known as "The Prese ...

the Preserver, and Shiva
Shiva (; sa, शिव, lit=The Auspicious One, Śiva ), also known as Mahadeva (; Help:IPA/Sanskrit, ɐɦaːd̪eːʋɐ, or Hara, is one of the Hindu deities, principal deities of Hinduism. He is the Supreme Being in Shaivism, one o ...

the Destroyer.
*The three Gunas found in Samkhya
''Samkhya'' or ''Sankya'' (; Sanskrit सांख्य), IAST: ') is a dualistic school of Indian philosophy. It views reality as composed of two independent principles, '' puruṣa'' (' consciousness' or spirit); and '' prakṛti'', (na ...

school of Hindu philosophy.
*The three paths to salvation in the ''Bhagavad Gita
The Bhagavad Gita (; sa, श्रीमद्भगवद्गीता, lit=The Song by God, translit=śrīmadbhagavadgītā;), often referred to as the Gita (), is a 700-Sanskrit prosody, verse Hindu texts, Hindu scripture that is part o ...

'' named Karma Yoga
Karma yoga ( sa, कर्म योग), also called Karma marga, is one of the four classical spiritual paths in Hinduism, one based on the "yoga of action", the others being Jnana yoga (path of knowledge), Rāja yoga (path of meditation ...

, Bhakti Yoga
Bhakti yoga ( sa, भक्ति योग), also called Bhakti marga (, literally the path of ''Bhakti''), is a spiritual path or spiritual practice within Hinduism focused on loving devotion towards any Personal god#Hinduism, personal deity. ...

and Jnana Yoga
Jnana yoga (), also known as the jnana ''marga'' (), is one of the Three Yogas , three classical paths (''Spirituality#Hinduism , margas'') for moksha (liberation) in Hinduism, which emphasizes the "path of knowledge", also known as the "path ...

.
Zoroastrianism

*The three virtues of ''Humata'', ''Hukhta'' and ''Huvarshta'' (Good Thoughts, Good Words and Good Deeds) are a basic tenet inZoroastrianism
Zoroastrianism is an Iranian religions, Iranian religion and one of the world's History of religion, oldest organized faiths, based on the teachings of the Iranian peoples, Iranian-speaking prophet Zoroaster. It has a Dualism in cosmology, du ...

.
Norse mythology

Three is a very significant number inNorse mythology
Norse, Nordic, or Scandinavian mythology is the body of myths belonging to the North Germanic peoples, stemming from Old Norse religion and continuing after the Christianization of Scandinavia, and into the Nordic folklore of the modern period. ...

, along with its powers 9 and 27.
*Prior to Ragnarök
In Norse mythology, (; non, wikt:ragnarǫk, Ragnarǫk) is a series of events, including a great battle, foretelling the death of numerous great figures (including the Æsir, gods Odin, Thor, Týr, Freyr, Heimdallr, and Loki), natural disast ...

, there will be three hard winters without an intervening summer, the Fimbulwinter.
*Odin endured three hardships upon the World Tree in his quest for the runes
Runes are the letter (alphabet), letters in a set of related alphabets known as runic alphabets native to the Germanic peoples. Runes were used to write various Germanic languages (with some exceptions) before they adopted the Latin alphabet, a ...

: he hanged himself, wounded himself with a spear, and suffered from hunger and thirst.
* Bor had three sons, Odin
Odin (; from non, Óðinn, ) is a widely revered Æsir, god in Germanic paganism. Norse mythology, the source of most surviving information about him, associates him with wisdom, healing, death, royalty, the gallows, knowledge, war, battle, v ...

, Vili, and Vé.
Other religions

*TheWicca
Wicca () is a Modern Paganism, modern Pagan religion. Religious studies, Scholars of religion categorise it as both a new religious movement and as part of the occultism, occultist stream of Western esotericism. It was developed in England duri ...

n Rule of Three.
*The Triple Goddess: Maiden, Mother, Crone; the three fates.
*The sons of Cronus
In Ancient Greek religion and Greek mythology, mythology, Cronus, Cronos, or Kronos ( or , from el, Κρόνος, ''Krónos'') was the leader and youngest of the first generation of Titans, the divine descendants of the Greek primordial de ...

: Zeus
Zeus or , , ; grc, Δῐός, ''Diós'', label=Genitive case, genitive Aeolic Greek, Boeotian Aeolic and Doric Greek#Laconian, Laconian grc-dor, Δεύς, Deús ; grc, Δέος, ''Déos'', label=Genitive case, genitive el, Δίας, ''D ...

, Poseidon
Poseidon (; grc-gre, wikt:Ποσειδῶν, Ποσειδῶν) was one of the Twelve Olympians in Religion in ancient Greece, ancient Greek religion and Greek mythology, myth, god of the sea, storms, earthquakes and horses.Burkert 1985pp. 1 ...

, and Hades
Hades (; grc-gre, ᾍδης, Háidēs; ), in the ancient Greek religion and Greek mythology, myth, is the god of the dead and the king of the Greek underworld, underworld, with which his name became synonymous. Hades was the eldest son of Cro ...

.
*The Slavic god Triglav
Triglav (; german: Terglau; it, Tricorno), with an elevation of , is the highest mountain in Slovenia and the highest peak of the Julian Alps. The mountain is the pre-eminent Coat of arms of Slovenia, symbol of the Slovene nation. It is the ce ...

has three heads.
Esoteric tradition

*TheTheosophical Society
The Theosophical Society, founded in 1875, is a worldwide body with the aim to advance the ideas of Theosophy in continuation of previous Theosophists, especially the Greek and Neoplatonism, Alexandrian Neo-Platonic philosophers dating back to 3r ...

has three conditions of membership.
*Gurdjieff
George Ivanovich Gurdjieff (; rus, Гео́ргий Ива́нович Гурджи́ев, r=Geórgy Ivánovich Gurdzhíev, p=ɡʲɪˈorɡʲɪj ɪˈvanəvʲɪd͡ʑ ɡʊrd͡ʐˈʐɨ(j)ɪf; hy, Գեորգի Իվանովիչ Գյուրջիև; c. 1 ...

's Three Centers and the Law of Three.
*''Liber AL vel Legis
''Liber AL vel Legis'' (), commonly known as ''The Book of the Law'', is the central sacred text of Thelema. Aleister Crowley said that it was dictated to him by a beyond-human being who called himself 'Aiwass'. Rose Edith Kelly, Crowley's w ...

'', the central scripture of the religion of Thelema
Thelema () is a Western esoteric and occult
The occult, in the broadest sense, is a category of esoteric supernatural
Supernatural refers to phenomena or entities that are beyond the laws of nature. The term is derived from Mediev ...

, consists of three chapters, corresponding to three divine narrators respectively: Nuit
Nuit (alternatively Nu, Nut, or Nuith) is a goddess in Thelema, the speaker in the first Chapter of '' The Book of the Law'', the sacred text written or received in 1904 by Aleister Crowley
Aleister Crowley (; born Edward Alexander Crowl ...

, Hadit
Hadit (sometimes Had) refers to a Thelemic deity. Hadit is the principal speaker of the second chapter of ''The Book of the Law
''Liber AL vel Legis'' (), commonly known as ''The Book of the Law'', is the central sacred text of Thele ...

and Ra-Hoor-Khuit
Heru-ra-ha () is a wikt:composite, composite deity within Thelema, a religion that began in 1904 with Aleister Crowley and his ''The Book of the Law, Book of the Law''. Heru-ra-ha is composed of #Active aspect, Ra-Hoor-Khuit and #Passive aspect, ...

.
*The Triple Greatness of Hermes Trismegistus
Hermes Trismegistus (from grc, Wiktionary:Ἑρμῆς, Ἑρμῆς ὁ Τρισμέγιστος, "Hermes the Thrice-Greatest"; Classical Latin: la, label=none, Mercurius ter Maximus) is a legendary Hellenistic figure that originated as a Syn ...

is an important theme in Hermeticism
Hermeticism, or Hermetism, is a philosophical system that is primarily based on the purported teachings of Hermes Trismegistus (a legendary Hellenistic combination of the Greek god Hermes and the Egyptian god Thoth). These teachings are containe ...

.
As a lucky or unlucky number

Three (, formal writing: ,pinyin
Hanyu Pinyin (), often shortened to just pinyin, is the official romanization system for Standard Chinese, Standard Mandarin Chinese in China, and to some extent, in Singapore and Malaysia. It is often used to teach Mandarin, normally writte ...

''sān'', Cantonese
Cantonese ( zh, t=廣東話, s=广东话, first=t, cy=Gwóngdūng wá) is a language within the Chinese (Sinitic) branch of the Sino-Tibetan languages originating from the city of Guangzhou (historically known as Canton) and its surrounding a ...

: ''saam''Chinese culture
Chinese culture () is one of the world's oldest cultures, originating thousands of years ago. The culture prevails across a large geographical region in East Asia and is extremely diverse and varying, with customs and traditions varying gre ...

because it sounds like the word "alive" ( pinyin ''shēng'', Cantonese: ''saang''Luck
Luck is the phenomenon and belief that defines the experience of improbable events, especially improbably positive or negative ones. The Naturalism (philosophy), naturalistic interpretation is that positive and negative events may happen at an ...

, especially bad luck, is often said to "come in threes".Seebad

in the ''Oxford Dictionary of Phrase and Fable'', 2006, via Encyclopedia.com.

Sports

* In American andCanadian football
Canadian football () is a team sport, sport played in Canada in which two teams of 12 players each compete for territorial control of a field of play long and wide attempting to advance a pointed oval-shaped ball into the opposing team's sco ...

, a field goal
A field goal (FG) is a means of scoring in gridiron football
Gridiron football,

is worth three points.
*In association football
Association football, more commonly known as football or soccer, is a team sport played between two teams of 11 Football player, players who primarily use their feet to propel the Ball (association football), ball around a rectangular field ca ...

:
** For purposes of league standings, since the mid-1990s almost all leagues have awarded three points for a win
Three points for a win is a standard used in many sports leagues and tournament#Group tournaments, group tournaments, especially in association football, in which three points are awarded to the team winning a match, with no points awarded to the l ...

.
** A team that wins three trophies in a season is said to have won a treble.
** A player who scores three goals in a match is said to have scored a hat-trick
A hat-trick or hat trick is the achievement of a generally positive feat three times in a match, or another achievement based on the number three.
Origin
The term first appeared in 1858 in cricket, to describe H. H. Stephenson taking three Wick ...

.
* In baseball
Baseball is a bat-and-ball games, bat-and-ball sport played between two team sport, teams of nine players each, taking turns batting (baseball), batting and Fielding (baseball), fielding. The game occurs over the course of several Pitch ...

:
** A batter strikes out upon the third strike in any single batting appearance.
** Each team's half of an inning ends once the defense has recorded three outs (unless the home team has a walk-off hit Walk-off may refer to:
*an event in a sporting event where the game-winning score immediately ends the game, such as a walk-off home run in baseball, a touchdown or field goal that's scored when there's no time left on the clock or during the ove ...

in the ninth inning or any extra inning).
** In scorekeeping, "3" denotes the first baseman.
*In basketball
Basketball is a team sport in which two teams, most commonly of five players each, opposing one another on a rectangular court, compete with the primary objective of shooting a basketball (approximately in diameter) through the defender' ...

:
** Three points are awarded for a basket made from behind a designated arc on the floor.
** The "3 position" is the small forward
The small forward (SF), also known as the three or swingman, is one of the five Basketball position, positions in a regulation basketball game. Small forwards are typically shorter, quicker, and leaner than Power forward (basketball), power forwar ...

.
*In bowling
Bowling is a Throwing sports#Target sports, target sport and recreational activity in which a player rolls a bowling ball, ball toward Bowling pin, pins (in pin bowling) or another target (in target bowling). The term ''bowling'' usually refer ...

, three strikes bowled consecutively is known as a "turkey".
* In cricket
Cricket is a Bat-and-ball games, bat-and-ball game played between two teams of eleven players on a cricket field, field at the centre of which is a cricket pitch, pitch with a wicket at each end, each comprising two Bail (cricket), bails b ...

, a bowler who is credited with dismissals of batsmen on three consecutive deliveries has achieved a "hat-trick".
*In Gaelic games
Gaelic games ( ga, Cluichí Gaelacha) are a set of sports played worldwide, though they are particularly popular in Ireland
Ireland ( ; ga, Éire ; Ulster Scots dialect, Ulster-Scots: ) is an island in the Atlantic Ocean, North Atla ...

(Gaelic football for men and women
A woman is an adult female human. Prior to adulthood, a female human is referred to as a girl (a female child or Adolescence, adolescent). The plural ''women'' is sometimes used in certain phrases such as "women's rights" to denote female hum ...

, hurling
Hurling ( ga, iománaíocht, ') is an outdoor Team sport, team game of ancient Gaelic culture, Gaelic Irish origin, played by men. One of Ireland's native Gaelic games, it shares a number of features with Gaelic football, such as the field ...

, and camogie
Camogie ( ; ga, camógaíocht ) is an Irish stick-and-ball team sport played by women. Camogie is played by 100,000 women in Ireland and worldwide, largely among Irish diaspora, Irish communities.
A variant of the game of hurling (which is pla ...

), three points are awarded for a goal, scored when the ball passes underneath the crossbar and between the goal posts.
*In ice hockey
Ice hockey (or simply hockey) is a team sport played on ice skates, usually on an Ice rink, ice skating rink with Ice hockey rink, lines and markings specific to the sport. It belongs to a family of sports called hockey. In ice hockey, two o ...

:
** Scoring three goals is called a "hat trick" (usually not hyphenated in North America).
** A team will typically have three forwards on the ice at any given time.
* In professional wrestling
Professional wrestling is a form of theater that revolves around staged wrestling matches. The mock combat is performed in a ring similar to the kind used in boxing, and the dramatic aspects of pro wrestling may be performed both in the ring or ...

, a pin is when one holds the opponent's shoulders against the mat for a count of three.
* In rugby union
Rugby union, commonly known simply as rugby, is a Contact sport#Terminology, close-contact team sport that originated at Rugby School in the first half of the 19th century. One of the Comparison of rugby league and rugby union, two codes of ru ...

:
** A successful penalty kick for goal or drop goal
A drop goal, field goal, or dropped goal is a method of scoring points in rugby union
Rugby union, commonly known simply as rugby, is a Contact sport#Terminology, close-contact team sport that originated at Rugby School in the first half of ...

is worth three points.
** In the French variation of the bonus points system, a team receives a bonus point in the league standings if it wins a match while scoring at least three more tries than its opponent.
** The starting tighthead prop wears the jersey number 3.
* In rugby league
Rugby league football, commonly known as just rugby league and sometimes football, footy, rugby or league, is a contact sport, full-contact sport played by two teams of thirteen players on a rectangular Rugby league playing field, field measur ...

:
** One of the two starting centres wears the jersey number 3. (An exception to this rule is the Super League
The Super League (officially known as the Betfred Super League due to sponsorship from Betfred and legally known as Super League Europe), is the top-level of the British rugby league system. At present the league consists of twelve teams, of wh ...

, which uses static squad numbering.)
*A " threepeat" is a term for winning three consecutive championships.
*A triathlon
A triathlon is an endurance multisport race consisting of Swimming (sport), swimming, Cycle sport, cycling, and running over various distances. Triathletes compete for fastest overall completion time, racing each segment sequentially with the t ...

consists of three events: swimming, bicycling, and running.
*In many sports a competitor or team is said to win a Triple Crown if they win three particularly prestigious competitions.
* In volleyball
Volleyball is a team sport in which two teams of six players are separated by a net. Each team tries to score points by grounding a ball on the other team's court under organized rules. It has been a part of the official program of the Summe ...

, once the ball is served, teams are allowed to touch the ball three times before being required to return the ball to the other side of the court, with the definition of "touch" being slightly different between indoor and beach volleyball.
Film

*A number of film versions of the novel ''The Three Musketeers
''The Three Musketeers'' (french: Les Trois Mousquetaires, links=no, ) is a French historical adventure novel written in 1844 by French author Alexandre Dumas. It is in the swashbuckler genre, which has heroic, chivalrous swordsmen who figh ...

'' by Alexandre Dumas
Alexandre Dumas (, ; ; born Dumas Davy de la Pailleterie (), 24 July 1802 – 5 December 1870), also known as Alexandre Dumas père (where '' '' is French for 'father', to distinguish him from his son Alexandre Dumas fils), was a French writer ...

: (1921
Events
January
* January 2
** The Association football club Cruzeiro Esporte Clube, from Belo Horizonte, is founded as the multi-sports club Palestra Italia by Italian expatriates in First Brazilian Republic, Brazil.
** The Spanish lin ...

, 1933
Events
January
* January 11 – Sir Charles Kingsford Smith makes the first commercial flight between Australia and New Zealand.
* January 17 – The United States Congress votes in favour of Philippines independence, against the wis ...

, 1948
Events January
* January 1
** The General Agreement on Tariffs and Trade (GATT) is inaugurated.
** The Constitution of New Jersey (later subject to amendment) goes into effect.
** The railways of Britain are nationalized, to form British ...

, 1973
Events January
* January 1
January 1 or 1 January is the first day of the year in the Gregorian Calendar. There are 364 days remaining until the end of the year (365 in leap years). This day is also known as New Year's Day since the ...

, 1992, 1993
File:1993 Events Collage.png, From left, clockwise: The Oslo I Accord is signed in an attempt to resolve the Israeli–Palestinian conflict; The White House (Moscow), Russian White House is shelled during the 1993 Russian constitutional crisis; Cze ...

and 2011
File:2011 Events Collage.png, From top left, clockwise: a protester partaking in Occupy Wall Street heralds the beginning of the Occupy movement; protests against Libyan dictator Muammar Gaddafi, who Assassination of Muammar Gaddafi, was killed tha ...

).
*'' 3 Days of the Condor'' (1975), starring Robert Redford
Charles Robert Redford Jr. (born August 18, 1936) is an American actor and filmmaker. He is the recipient of various accolades, including an Academy Award from four nominations, a British Academy Film Award, two Golden Globe Awards, the Ce ...

, Faye Dunaway
Dorothy Faye Dunaway (born January 14, 1941) is an American actress. She is the recipient of List of awards and nominations received by Faye Dunaway, many accolades, including an Academy Awards, Academy Award, a Primetime Emmy Award, three Golden ...

, Cliff Robertson
Clifford Parker Robertson III (September 9, 1923 – September 10, 2011) was an American actor whose career in film and television spanned over six decades. Robertson portrayed a young John F. Kennedy
John Fitzgerald Kennedy (May 29, 191 ...

, and Max von Sydow
Max von Sydow ( , ; born Carl Adolf von Sydow; 10 April 1929 – 8 March 2020) was a Swedish-French actor. He had a 70-year career in European and American cinema, television, and theatre, appearing in more than 150 films and several television ...

.
*''Three Amigos
''Three Amigos'' (stylized as ''¡Three Amigos!'') is a 1986 American Western comedy film
A comedy film is a category of film
A film also called a movie, motion picture, moving picture, picture, photoplay or (slang) flick is ...

'' (1986), comedy film starring Steve Martin
Stephen Glenn Martin (born August 14, 1945) is an American actor, comedian, writer, producer, and musician. He has won five Grammy Awards, a Primetime Emmy Award, and was awarded an Honorary Academy Award in 2013. Additionally, he was nominated ...

, Chevy Chase
Cornelius Crane "Chevy" Chase (; born October 8, 1943) is an American comedian, actor and writer. He became a key cast member in the first season of ''Saturday Night Live'', where his recurring ''Weekend Update'' segment became a staple of the ...

, and Martin Short
Martin Hayter Short (born March 26, 1950) is a Canadian-American actor, comedian, and writer. He has List of awards and nominations received by Martin Short, received various awards including two Primetime Emmy Awards, and a Tony Award. In 2 ...

.
*''Three Kings
The biblical Magi from Middle Persian ''moɣ''(''mard'') from Old Persian ''magu-'' 'Zoroastrian clergyman' ( or ; singular: ), also referred to as the (Three) Wise Men or (Three) Kings, also the Three Magi were distinguished foreigners in the G ...

'' (1999), starring George Clooney
George Timothy Clooney (born May 6, 1961) is an American actor and filmmaker. He is the recipient of List of awards and nominations received by George Clooney, numerous accolades, including a British Academy Film Awards, British Academy Film A ...

, Mark Wahlberg
Mark Robert Michael Wahlberg (born June 5, 1971), former stage name Marky Mark, is an American actor, businessman, and former rapper. He has received List of awards and nominations received by Mark Wahlberg, multiple accolades, including a B ...

, Ice Cube
An ice cube is a small piece of ice, which is typically Rectangle, rectangular as viewed from above and trapezoidal as viewed from the side. Ice cubes are products of mechanical refrigeration and are usually produced to cool beverages. They ma ...

, and Spike Jonze
Adam H. Spiegel (born October 22, 1969), known professionally as Spike Jonze, is an American filmmaker, actor, musician, and photographer. His work includes commercials, film, music videos, skateboard videos and television.
Jonze began his ca ...

.
*'' 3 Days to Kill'' (2014), starring Kevin Costner
Kevin Michael Costner (born January 18, 1955) is an American actor, producer, film director and musician. He has received List of awards and nominations received by Kevin Costner, various accolades, including two Academy Awards, two Golden Glob ...

.
*''Three Billboards Outside Ebbing, Missouri
''Three Billboards Outside Ebbing, Missouri'' is a 2017 Crime drama, crime drama film written, directed, and co-produced by Martin McDonagh and starring Frances McDormand as a Missouri woman who rents three roadside billboards to draw attention ...

'' (2017), starring Frances McDormand
Frances Louise McDormand (born Cynthia Ann Smith; June 23, 1957) is an American actress and producer. Throughout her career spanning over four decades, McDormand has received list of awards and nominations received by Frances McDormand, numerou ...

, Woody Harrelson
Woodrow Tracy Harrelson (born July 23, 1961) is an American actor and playwright. He is the recipient of List of awards and nominations received by Woody Harrelson, various accolades, including a Primetime Emmy Award and two Screen Actors Guild ...

, Sam Rockwell
Sam Rockwell (born November 5, 1968) is an American actor. He is known for appearing in independent films and also as a character actor portraying a wide variety of roles both comedic and dramatic in films such as ''Lawn Dogs'' (1997 ...

.
See also

*Cube (algebra)
In arithmetic and algebra, the cube of a number is its third exponentiation, power, that is, the result of multiplying three instances of together.
The cube of a number or any other expression (mathematics), mathematical expression is denote ...

– (3 superscript
A subscript or superscript is a character (such as a number or letter) that is set slightly below or above the normal line of type, respectively. It is usually smaller than the rest of the text. Subscripts appear at or below the Baseline (typog ...

)
*Third
Third or 3rd may refer to:
Numbers
* 3rd, the ordinal form of the cardinal number 3
* , a fraction
A fraction (from la, fractus, "broken") represents a part of a whole or, more generally, any number of equal parts. When spoken in everyd ...

* Triad
* Rule of three
*List of highways numbered 3
The following highways are numbered 3, H-3, PRI-3, AH3, E03 and R3. For roads numbered A3, see A3 roads. For roads numbered M3, see M3 (disambiguation)#Roads, M3. For roads numbered N3, see N3 (disambiguation)#Roads, N3. For roads numbered 3A, see ...

References

*Wells, D. '' The Penguin Dictionary of Curious and Interesting Numbers'' London: Penguin Group. (1987): 46–48External links

Tricyclopedic Book of Threes

by Michael Eck

by Dr. John A. McNulty *

The Number 3

The Positive Integer 3

{{DEFAULTSORT:3 (Number) Integers