3 (three) is a number
. It is the natural number
and preceding 4
, and is the smallest odd prime number
and the only prime preceding a square number
. 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 and Chinese numerals
) that are still in use. That was also the original representation of 3 in the Brahmic
(Indian) numerical notation. However, during the Gupta Empire
the sign was modified by the addition of a curve on each line. The Nagari
rotated the lines clockwise, 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
in the 9th century. The bottom stroke was dropped around the 10th century in the western parts of the Caliphate, such as the Maghreb
, 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
In most modern Western typeface
s, the digit 3, like the other decimal digit
s, has the height of a capital letter
, and sits on the baseline
. In typefaces with text figures
, on the other hand, the glyph usually has the height of a lowercase letter
"x" and a descender
". 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 obstruct changing a three into an eight with fraudulent intent. It is found on UPC-A
barcodes and standard 52-card deck
*a rough approximation of
(3.1415...) and a very rough approximation of ''e''
(2.71828..) when doing quick estimates.
*the number of non-collinear points needed to determine a plane
and a circle
*the first odd prime number
and the second smallest prime.
*the first Fermat prime
*the first Mersenne prime
*the second Sophie Germain prime
*the second Mersenne prime exponent.
*the second factorial prime
*the second Lucas prime
*the second triangular number
. It is the only prime triangular number.
*the fourth Fibonacci number
*the smallest number of sides that a simple (non-self-intersecting) polygon
Three is the only prime which is one less than a perfect square
. Any other number which is for some integer ''n'' is not prime, since it is . This is true for 3 as well (with ), but in this case the smaller factor is 1. If ''n'' is greater than 2, both and are greater than 1 so their product is not prime.
A natural number
by three if the sum of its digits
in base 10
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
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
. This works in base 10
and in any positional numeral system
divided by three leaves a remainder of one (bases 4, 7, 10, etc.).
Three of the five Platonic solids
have triangular faces – the tetrahedron
, the octahedron
, and the icosahedron
. Also, three of the five Platonic solids have vertices
where three faces meet – the tetrahedron
, the hexahedron
), and the dodecahedron
. Furthermore, only three different types of polygons
comprise the faces of the five Platonic solids – the triangle
, the square
, and the pentagon
There are only three distinct 4×4 panmagic square
According to Pythagoras
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.
The trisection of the angle
was one of the three famous problems of antiquity.
proved that every integer is the sum of at most 3 triangular numbers
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
*The Roman numeral III stands for giant star
in the Yerkes spectral classification scheme
*Three is the atomic number
*Three is the ASCII
code of "End of Text
*Three is the number of dimensions
that humans can perceive. Humans perceive the universe
to have three spatial dimensions
, but some theories, such as string theory
, suggest there are more.
*Three is the number of elementary fermion generations
according to the Standard Model
of particle physics.
, a polygon
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
to distinguish color
s is based upon the varying sensitivity of different cells in the retina
to light of different wavelengths
. Humans being trichromatic
, the retina contains three types of color receptor cells, or cones
*There are three primary color
s in the additive
*In European alchemy
, the three primes ( la|tria prima) were salt
() and mercury
[Eric John Holmyard. ''Alchemy.'' 1995. p.153]
*The three doshas
(weaknesses) and their antidote
s are the basis of Ayurvedic medicine
*Three is the symbolic representation for Mu
, Augustus Le Plongeon
's and James Churchward
's lost continent.
*Philosophers such as Aquinas
, C. S. Peirce
, and Karl Popper
have made threefold divisions, or ''trichotomies
'', which have been important in their work.
of Thesis + Antithesis = Synthesis
creates three-ness from two-ness.
Many world religions contain triple deities or concepts of trinity, including:
*the Hindu Trimurti
*the Hindu Tridevi
*the Three Jewels
*the Three Pure Ones
*the Christian Holy Trinity
*the Triple Goddess
*The threefold office
of Christ is a Christian doctrine which states that Christ performs the functions of prophet
, and king
*The ministry of Jesus
lasted approximately three years.
*During the Agony in the Garden
, 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
*Saint Peter thrice denied Jesus
and thrice affirmed his faith in Jesus
– wise men who were astronomers/astrologers from Persia – gave Jesus three gifts.
*There are three Synoptic Gospels
and three epistles of John
*Paul the Apostle
went blind for three days after his conversion to Christianity
had three sons: Ham
*The Three Patriarchs
*The prophet Balaam
beat his donkey three times.
*The prophet Jonah
spent three days and nights in the belly of a large fish
*Three divisions of the Written Torah
(Five Books of Moses), Nevi'im
*Three divisions of the Jewish people: Kohen
*Three daily prayers
*Shabbat ends when three stars are visible in the night sky
*Three Pilgrimage Festivals
s on the Passover Seder
*The Three Weeks
, a period of mourning bridging the fast days of Seventeenth of Tammuz
and Tisha B'Av
*Three cardinal sins for which a Jew must die rather than transgress: idolatry
, sexual immorality
, a Jewish boy's first haircut at age 3
*A Beth din
is composed of three members
are traditionally turned away three times to test their sincerity
*In the Jewish mystical
tradition of the Kabbalah
, it is believed that the soul
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
(Hebrew: ''Etz ha-Chayim'', עץ החיים) refers to a latter 3-pillar diagrammatic representation of its central mystical symbol, known as the ''10 Sephirot
*The Triple Bodhi
(ways to understand the end of birth) are Budhu, Pasebudhu, and Mahaarahath.
*The Three Jewels
, the three things that Buddhists take refuge
*The Imperial Regalia of Japan
of the sword, mirror, and jewel.
*The Three Treasures
(), the basic virtues
*The Three Dantian
*Three Lines of a Trigram
: Heaven Fu Xi
(Hand – Head – 3º Eye), Humanity Shen Nong
), Hell Nüwa
(Foot – Abdomen – Umbiculus).
the Creator, Vishnu
the Preserver, and Shiva
*The three Gunas
found in Samkhya
school of Hindu philosophy.
*The three paths to salvation in the ''Bhagavad Gita
'' named Karma Yoga
, Bhakti Yoga
and Jnana Yoga
*The three virtues of ''Humata'', ''Hukhta'' and ''Huvarshta'' (Good Thoughts, Good Words and Good Deeds) are a basic tenet in Zoroastrianism
Three is a very significant number in Norse mythology
, along with its powers 9 and 27.
*Prior to Ragnarök
, 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
: he hanged himself, wounded himself with a spear, and suffered from hunger and thirst.
had three sons, Odin
, and Vé
n Rule of Three
*The Triple Goddess
: Maiden, Mother, Crone; the three fates.
*The sons of Cronus
, and Hades
*The Slavic god Triglav
has three heads.
*The Theosophical Society
has three conditions of membership
's Three Centers
and the Law of Three
*''Liber AL vel Legis
'', the central scripture of the religion of Thelema
, consists of three chapters, corresponding to three divine narrators respectively: Nuit
*The Triple Greatness of Hermes Trismegistus
is an important theme in Hermeticism
As a lucky or unlucky number
Three (, formal writing: , pinyin
) is considered a good number
in Chinese culture
because it sounds like the word "alive" ( pinyin ''shēng'', Cantonese: ''saang''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 forbidden
, especially bad luck, is often said to "come in threes".
in the ''Oxford Dictionary of Phrase and Fable'', 2006, via Encyclopedia.com.
* In American
and Canadian football
, a field goal
is worth three points.
*In association football
** For purposes of league standings, since the mid-1990s almost all leagues have awarded three points for a win
** 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
* In baseball
** 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
in the ninth inning or any extra inning).
** In scorekeeping, "3" denotes the first baseman.
** Three points
are awarded for a basket made from behind a designated arc on the floor.
** The "3 position" is the small forward
, three strikes
bowled consecutively is known as a "turkey".
* In cricket
, a bowler who is credited with dismissals of batsmen on three consecutive deliveries has achieved a "hat-trick".
*In Gaelic games
(Gaelic football for men
, and camogie
), three points are awarded for a goal, scored when the ball passes underneath the crossbar and between the goal posts.
*In ice hockey
** 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
, a pin
is when one holds the opponent's shoulders against the mat for a count of three.
* In rugby union
** A successful penalty kick for goal
or drop goal
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
** One of the two starting centres wears the jersey number 3. (An exception to this rule is the Super League
, which uses static squad numbering.)
" is a term for winning three consecutive championships.
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
, 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.
*A number of film versions of the novel ''The Three Musketeers
'' by Alexandre Dumas
, 1992, 1993
*''3 Days of the Condor
'' (1975), starring Robert Redford
, Faye Dunaway
, Cliff Robertson
, and Max von Sydow
'' (1986), comedy film starring Steve Martin
, Chevy Chase
, and Martin Short
'' (1999), starring George Clooney
, Mark Wahlberg
, Ice Cube
, and Spike Jonze
*''3 Days to Kill
'' (2014), starring Kevin Costner
*''Three Billboards Outside Ebbing, Missouri
'' (2017), starring Frances McDormand
, Woody Harrelson
, Sam Rockwell
from ''Despicable Me
'' have three digits
on their hands.
– (3 superscript
*List of highways numbered 3
*Wells, D. ''The Penguin Dictionary of Curious and Interesting Numbers
'' London: Penguin Group. (1987): 46–48
Tricyclopedic Book of Threes
by Michael Eck
by Dr. John A. McNulty
*The Number 3The Positive Integer 3