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9 (nine) 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 ...
following and preceding .


Evolution of the Arabic digit

In the
beginning Beginning may refer to: * ''Beginning'' (album), by Pakho Chau * ''Beginning'' (play), a 2017 play by David Eldridge * ''Beginning'' (film), a Georgian-French drama film *"Beginning", a song by heavy metal band Kotipelto *"Beginning", a 2018 trac ...
, various Indians wrote a digit 9 similar in shape to the modern closing
question mark The question mark (also known as interrogation point, query, or eroteme in journalism) is a punctuation mark that indicates an interrogative clause or phrase in many languages. History In the fifth century, Syriac Bible manuscripts used que ...
without the bottom dot. The Kshatrapa, Andhra and Gupta started curving the bottom vertical line coming up with a -look-alike. The Nagari continued the bottom stroke to make a circle and enclose the 3-look-alike, in much the same way that the sign @ encircles a lowercase ''a''. As time went on, the enclosing circle became bigger and its line continued beyond the circle downwards, as the 3-look-alike became smaller. Soon, all that was left of the 3-look-alike was a squiggle. The Arabs simply connected that squiggle to the downward stroke at the middle and subsequent European change was purely cosmetic. While the shape of the glyph for the digit 9 has an ascender in most modern
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 thousands o ...
s, 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 ...
the character usually has 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'' c ...
, as, for example, in . The modern digit resembles an inverted ''6''. To disambiguate the two on objects and documents that can be inverted, they are often underlined. Another distinction from the 6 is that it is sometimes handwritten with two strokes and a straight stem, resembling a raised lower-case letter q. In a
seven-segment display A seven-segment display is a form of electronic display device for displaying decimal numerals that is an alternative to the more complex dot matrix displays. Seven-segment displays are widely used in digital clocks, electronic meters, basic ...
, the number 9 can be constructed in two ways, either with a hook at the end of its stem or without one. Most LCD calculators use the former, but some
VFD VFD may refer to: * Factory Workers' Union of Germany, (german: Verband der Fabrikarbeiter Deutschlands, link=no), a former trade union in Germany * Vacuum fluorescent display, a display device on consumer electronics equipment * Variable-freque ...
models use the latter.


Mathematics

Nine is the fourth
composite number A composite number is a positive integer that can be formed by multiplying two smaller positive integers. Equivalently, it is a positive integer that has at least one divisor other than 1 and itself. Every positive integer is composite, prime, ...
, and the first composite number that is odd. 9 is the highest single-digit number in the decimal system. It is the third
square number In mathematics, a square number or perfect square is an integer that is the square of an integer; in other words, it is the product of some integer with itself. For example, 9 is a square number, since it equals and can be written as . The usu ...
(32), and the second non-unitary square
prime 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 ways ...
of the form ''p''2 and first that is odd, with all subsequent squares of this form odd as well. By
Mihăilescu's theorem Catalan's conjecture (or Mihăilescu's theorem) is a theorem in number theory that was conjectured by the mathematician Eugène Charles Catalan in 1844 and proven in 2002 by Preda Mihăilescu at Paderborn University. The integers 23 and 32 are ...
, 9 is the only positive
perfect power In mathematics, a perfect power is a natural number that is a product of equal natural factors, or, in other words, an integer that can be expressed as a square or a higher integer power of another integer greater than one. More formally, ''n'' ...
that is one more than another positive perfect power, since the
square In Euclidean geometry, a square is a regular quadrilateral, which means that it has four equal sides and four equal angles (90- degree angles, π/2 radian angles, or right angles). It can also be defined as a rectangle with two equal-length a ...
of 3 is one more than the cube of 2. A number that is 4 or 5 modulo 9 cannot be represented as the sum of three cubes. 9 is a
Motzkin number In mathematics, the th Motzkin number is the number of different ways of drawing non-intersecting chords between points on a circle (not necessarily touching every point by a chord). The Motzkin numbers are named after Theodore Motzkin and have d ...
, for the number of ways of drawing non-intersecting
chords Chord may refer to: * Chord (music), an aggregate of musical pitches sounded simultaneously ** Guitar chord a chord played on a guitar, which has a particular tuning * Chord (geometry), a line segment joining two points on a curve * Chord ( ...
between four points on a
circle A circle is a shape consisting of all points in a plane that are at a given distance from a given point, the centre. Equivalently, it is the curve traced out by a point that moves in a plane so that its distance from a given point is con ...
. Since , 9 is an exponential factorial. Six recurring nines appear in the decimal places 762 through 767 of . (See
six nines in pi A sequence of six consecutive nines occurs in the decimal representation of the number pi (), starting at the 762nd decimal place.. It has become famous because of the mathematical coincidence and because of the idea that one could memorize the d ...
). The first non-trivial magic square is a 3 x 3 magic square made of nine cells, with a magic constant of 15; there are no 2 x 2 magic squares with four cells. Meanwhile, a 9 x 9 magic square has a magic constant of 369. 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 two to ...
with nine sides is called a
nonagon In geometry, a nonagon () or enneagon () is a nine-sided polygon or 9-gon. The name ''nonagon'' is a prefix hybrid formation, from Latin (''nonus'', "ninth" + ''gonon''), used equivalently, attested already in the 16th century in French ''nonogo ...
. Also an ''enneagon'', it is able to fill a plane-vertex alongside an
equilateral triangle In geometry, an equilateral triangle is a triangle in which all three sides have the same length. In the familiar Euclidean geometry, an equilateral triangle is also equiangular; that is, all three internal angles are also congruent to each oth ...
and an regular
octadecagon In geometry, an octadecagon (or octakaidecagon) or 18-gon is an eighteen-sided polygon. Regular octadecagon A '' regular octadecagon'' has a Schläfli symbol and can be constructed as a quasiregular truncated enneagon, t, which alternates tw ...
, or 18-sided
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 two to ...
. There are nine distinct
uniform coloring In geometry, a uniform coloring is a property of a uniform figure (uniform tiling or uniform polyhedron) that is colored to be vertex-transitive. Different symmetries can be expressed on the same geometric figure with the faces following differ ...
s of the
triangular tiling In geometry, the triangular tiling or triangular tessellation is one of the three regular tilings of the Euclidean plane, and is the only such tiling where the constituent shapes are not parallelogons. Because the internal angle of the equilate ...
and the
square tiling In geometry, the square tiling, square tessellation or square grid is a regular tiling of the Euclidean plane. It has Schläfli symbol of meaning it has 4 squares around every vertex. Conway called it a quadrille. The internal angle of th ...
, which are the two simplest
regular tilings This article lists the regular polytopes and regular polytope compounds in Euclidean, spherical and hyperbolic spaces. The Schläfli symbol describes every regular tessellation of an ''n''-sphere, Euclidean and hyperbolic spaces. A Schläfli sy ...
; the hexagonal tiling, on the other hand, has three distinct uniform colorings. There are nine
edge-transitive In geometry, a polytope (for example, a polygon or a polyhedron) or a tiling is isotoxal () or edge-transitive if its symmetries act transitively on its edges. Informally, this means that there is only one type of edge to the object: given t ...
convex polyhedra in
three dimensions Three-dimensional space (also: 3D space, 3-space or, rarely, tri-dimensional space) is a geometric setting in which three values (called ''parameters'') are required to determine the position of an element (i.e., point). This is the informa ...
: *the five regular Platonic solids: the
tetrahedron In geometry, a tetrahedron (plural: tetrahedra or tetrahedrons), also known as a triangular pyramid, is a polyhedron composed of four triangular faces, six straight edges, and four vertex corners. The tetrahedron is the simplest of all th ...
,
octahedron In geometry, an octahedron (plural: octahedra, octahedrons) is a polyhedron with eight faces. The term is most commonly used to refer to the regular octahedron, a Platonic solid composed of eight equilateral triangles, four of which meet at ea ...
, cube,
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 ...
and icosahedron; *the two quasiregular Archimedean solids: the
cuboctahedron A cuboctahedron is a polyhedron with 8 triangular faces and 6 square faces. A cuboctahedron has 12 identical vertices, with 2 triangles and 2 squares meeting at each, and 24 identical edges, each separating a triangle from a square. As such, it ...
and the
icosidodecahedron In geometry, an icosidodecahedron is a polyhedron with twenty (''icosi'') triangular faces and twelve (''dodeca'') pentagonal faces. An icosidodecahedron has 30 identical vertices, with two triangles and two pentagons meeting at each, and 60 i ...
; and *two
Catalan solid In mathematics, a Catalan solid, or Archimedean dual, is a dual polyhedron to an Archimedean solid. There are 13 Catalan solids. They are named for the Belgian mathematician Eugène Catalan, who first described them in 1865. The Catalan s ...
s: the
rhombic dodecahedron In geometry, the rhombic dodecahedron is a convex polyhedron with 12 congruent rhombic faces. It has 24 edges, and 14 vertices of 2 types. It is a Catalan solid, and the dual polyhedron of the cuboctahedron. Properties The rhombic dodecahed ...
and the
rhombic triacontahedron In geometry, the rhombic triacontahedron, sometimes simply called the triacontahedron as it is the most common thirty-faced polyhedron, is a convex polyhedron with 30 rhombic faces. It has 60 edges and 32 vertices of two types. It is a Ca ...
, which are
duals ''Duals'' is a compilation album by the Irish rock band U2. It was released in April 2011 to u2.com subscribers. Track listing :* "Where the Streets Have No Name" and "Amazing Grace" are studio mix of U2's performance at the Rose Bowl, P ...
to the only two quasiregular polyhedra. In four-dimensional space, there are nine paracompact hyperbolic honeycomb
Coxeter group In mathematics, a Coxeter group, named after H. S. M. Coxeter, is an abstract group that admits a formal description in terms of reflections (or kaleidoscopic mirrors). Indeed, the finite Coxeter groups are precisely the finite Euclidean refle ...
s, as well as nine regular compact hyperbolic honeycombs from regular
convex Convex or convexity may refer to: Science and technology * Convex lens, in optics Mathematics * Convex set, containing the whole line segment that joins points ** Convex polygon, a polygon which encloses a convex set of points ** Convex polytop ...
and star '' polychora''. There are also nine uniform demitesseractic (\mathrm D_) Euclidean honeycombs in the fourth dimension. There are only three types of Coxeter groups of uniform figures in dimensions
nine 9 is a number, numeral, and glyph. 9 or nine may also refer to: Dates * AD 9, the ninth year of the AD era * 9 BC, the ninth year before the AD era * 9, numerical symbol for the month of September Places * Nine, Portugal, a parish in the ...
and thereafter, aside from the many families of prisms and
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: the \mathrm A_ simplex groups, the \mathrm B_ hypercube groups, and the \mathrm D_
demihypercube In geometry, demihypercubes (also called ''n-demicubes'', ''n-hemicubes'', and ''half measure polytopes'') are a class of ''n''- polytopes constructed from alternation of an ''n''- hypercube, labeled as ''hγn'' for being ''half'' of the hy ...
groups. The ninth dimension is also the final dimension that contains Coxeter-Dynkin diagrams as uniform solutions in
hyperbolic space In mathematics, hyperbolic space of dimension n is the unique simply connected, n-dimensional Riemannian manifold of constant sectional curvature equal to -1. It is homogeneous, and satisfies the stronger property of being a symmetric space. The ...
. Inclusive of compact hyperbolic solutions, there are a total of 238 compact and paracompact Coxeter-Dynkin diagrams between dimensions two and nine, or equivalently between ranks three and ten. The most important of the last _9 paracompact groups is the group _9 with 1023 total honeycombs, the simplest of which is 621 whose
vertex figure In geometry, a vertex figure, broadly speaking, is the figure exposed when a corner of a polyhedron or polytope is sliced off. Definitions Take some corner or vertex of a polyhedron. Mark a point somewhere along each connected edge. Draw line ...
is the 521 honeycomb: the vertex arrangement of the densest-possible packing of spheres in 8 dimensions which forms the \mathbb E_ lattice. The 621 honeycomb is made of
9-simplex In geometry, a 9- simplex is a self-dual regular 9-polytope. It has 10 vertices, 45 edges, 120 triangle faces, 210 tetrahedral cells, 252 5-cell 4-faces, 210 5-simplex 5-faces, 120 6-simplex 6-faces, 45 7-simplex 7-faces, and 10 8-simplex 8-fa ...
es and 9-orthoplexes, with 1023 total polytope elements making up each 9-simplex. It is the final honeycomb figure with infinite facets and vertex figures in the k21 family of
semiregular polytope In geometry, by Thorold Gosset's definition a semiregular polytope is usually taken to be a polytope that is vertex-transitive and has all its facets being regular polytopes. E.L. Elte compiled a longer list in 1912 as ''The Semiregular Polyt ...
s, first defined by
Thorold Gosset John Herbert de Paz Thorold Gosset (16 October 1869 – December 1962) was an English lawyer and an amateur mathematician. In mathematics, he is noted for discovering and classifying the semiregular polytopes in dimensions four and higher, a ...
in 1900. There are nine Heegner numbers, or square-free positive integers n that yield an imaginary
quadratic field In algebraic number theory, a quadratic field is an algebraic number field of degree two over \mathbf, the rational numbers. Every such quadratic field is some \mathbf(\sqrt) where d is a (uniquely defined) square-free integer different from 0 a ...
\Q\left sqrt\right/math> whose ring of integers has a
unique factorization In mathematics, a unique factorization domain (UFD) (also sometimes called a factorial ring following the terminology of Bourbaki) is a ring in which a statement analogous to the fundamental theorem of arithmetic holds. Specifically, a UFD is a ...
, or class number of 1.


In decimal

A positive number is divisible by nine
if and only if In logic and related fields such as mathematics and philosophy, "if and only if" (shortened as "iff") is a biconditional logical connective between statements, where either both statements are true or both are false. The connective is b ...
its
digital root The digital root (also repeated digital sum) of a natural number in a given radix is the (single digit) value obtained by an iterative process of summing digits, on each iteration using the result from the previous iteration to compute a digit su ...
is nine. That is, if any
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 ...
is multiplied by 9, and the digits of the answer are repeatedly added until it is just one digit, the sum will be nine: *2 × 9 = 18 (1 + 8 = 9) *3 × 9 = 27 (2 + 7 = 9) *9 × 9 = 81 (8 + 1 = 9) *121 × 9 = 1089 (1 + 0 + 8 + 9 = 18; 1 + 8 = 9) *234 × 9 = 2106 (2 + 1 + 0 + 6 = 9) *578329 × 9 = 5204961 (5 + 2 + 0 + 4 + 9 + 6 + 1 = 27; 2 + 7 = 9) *482729235601 × 9 = 4344563120409 (4 + 3 + 4 + 4 + 5 + 6 + 3 + 1 + 2 + 0 + 4 + 0 + 9 = 45; 4 + 5 = 9) There are other interesting patterns involving multiples of nine: *12345679 × 9 = 111111111 *12345679 × 18 = 222222222 *12345679 × 81 = 999999999 This works for all the multiples of 9. is the only other such that a number is divisible by ''n'' if and only if its digital root is divisible by ''n''. In base-''N'', the
divisor 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 ...
s of have this property. Another consequence of 9 being , is that it is also a
Kaprekar number In mathematics, a natural number in a given number base is a p-Kaprekar number if the representation of its square in that base can be split into two parts, where the second part has p digits, that add up to the original number. The numbers are n ...
. The difference between a base-10 positive integer and the sum of its digits is a whole multiple of nine. Examples: *The sum of the digits of 41 is 5, and 41 − 5 = 36. The digital root of 36 is 3 + 6 = 9, which, as explained above, demonstrates that it is divisible by nine. *The sum of the digits of 35967930 is 3 + 5 + 9 + 6 + 7 + 9 + 3 + 0 = 42, and 35967930 − 42 = 35967888. The digital root of 35967888 is 3 + 5 + 9 + 6 + 7 + 8 + 8 + 8 = 54, 5 + 4 = 9. If dividing a number by the amount of 9s corresponding to its number of digits, the number is turned into a
repeating decimal A repeating decimal or recurring decimal is decimal representation of a number whose digits are periodic (repeating its values at regular intervals) and the infinitely repeated portion is not zero. It can be shown that a number is rational if a ...
. (e.g. )
Casting out nines Casting out nines is any of three arithmetical procedures: *Adding the decimal digits of a positive whole number, while optionally ignoring any 9s or digits which sum to a multiple of 9. The result of this procedure is a number which is smaller th ...
is a quick way of testing the calculations of sums, differences, products, and quotients of integers known as long ago as the 12th century.


List of basic calculations


Alphabets and codes

*In the
NATO phonetic alphabet The (International) Radiotelephony Spelling Alphabet, commonly known as the NATO phonetic alphabet, is the most widely used set of clear code words for communicating the letters of the Roman alphabet, technically a ''radiotelephonic spellin ...
, the digit 9 is called "Niner". *Five-digit
produce Produce is a generalized term for many farm-produced crops, including fruits and vegetables (grains, oats, etc. are also sometimes considered ''produce''). More specifically, the term ''produce'' often implies that the products are fresh and g ...
PLU codes that begin with 9 are organic.


Culture and mythology


Indian culture

Nine is a number that appears often in
Indian culture Indian culture is the heritage of social norms, ethical values, traditional customs, belief systems, political systems, artifacts and technologies that originated in or are associated with the ethno-linguistically diverse India. The term al ...
and mythology. Some instances are enumerated below. *Nine
influencers An Internet celebrity (also known as a social media influencer, social media personality, internet personality, or simply influencer) is a celebrity who has acquired or developed their fame and notability through the Internet. The rise of social m ...
are attested in
Indian astrology Jyotisha or Jyotishya (from Sanskrit ', from ' “light, heavenly body" and ''ish'' - from Isvara or God) is the traditional Hindu system of astrology, also known as Hindu astrology, Indian astrology and more recently Vedic astrology. It is one ...
. *In the
Vaisheshika Vaisheshika or Vaiśeṣika ( sa, वैशेषिक) is one of the six schools of Indian philosophy (Vedic systems) from ancient India. In its early stages, the Vaiśeṣika was an independent philosophy with its own metaphysics, epistemolog ...
branch of
Hindu philosophy Hindu philosophy encompasses the philosophies, world views and teachings of Hinduism that emerged in Ancient India which include six systems ('' shad-darśana'') – Samkhya, Yoga, Nyaya, Vaisheshika, Mimamsa and Vedanta.Andrew Nicholson ( ...
, there are nine universal substances or elements:
Earth Earth is the third planet from the Sun and the only astronomical object known to harbor life. While large volumes of water can be found throughout the Solar System, only Earth sustains liquid surface water. About 71% of Earth's surfa ...
,
Water Water (chemical formula ) is an Inorganic compound, inorganic, transparent, tasteless, odorless, and Color of water, nearly colorless chemical substance, which is the main constituent of Earth's hydrosphere and the fluids of all known living ...
,
Air The atmosphere of Earth is the layer of gases, known collectively as air, retained by Earth's gravity that surrounds the planet and forms its planetary atmosphere. The atmosphere of Earth protects life on Earth by creating pressure allowing f ...
,
Fire Fire is the rapid oxidation of a material (the fuel) in the exothermic chemical process of combustion, releasing heat, light, and various reaction products. At a certain point in the combustion reaction, called the ignition point, flames a ...
,
Ether In organic chemistry, ethers are a class of compounds that contain an ether group—an oxygen atom connected to two alkyl or aryl groups. They have the general formula , where R and R′ represent the alkyl or aryl groups. Ethers can again be ...
,
Time Time is the continued sequence of existence and events that occurs in an apparently irreversible succession from the past, through the present, into the future. It is a component quantity of various measurements used to sequence events, ...
,
Space Space is the boundless three-dimensional extent in which objects and events have relative position and direction. In classical physics, physical space is often conceived in three linear dimensions, although modern physicists usually cons ...
,
Soul In many religious and philosophical traditions, there is a belief that a soul is "the immaterial aspect or essence of a human being". Etymology The Modern English noun '' soul'' is derived from Old English ''sāwol, sāwel''. The earliest atte ...
, and Mind. *
Navaratri Navaratri is an annual Hindu festival observed in the honour of the goddess Durga. It spans over nine nights (and ten days), first in the month of Chaitra (March/April of the Gregorian calendar), and again in the month of Sharada. It is o ...
is a nine-day festival dedicated to the
nine 9 is a number, numeral, and glyph. 9 or nine may also refer to: Dates * AD 9, the ninth year of the AD era * 9 BC, the ninth year before the AD era * 9, numerical symbol for the month of September Places * Nine, Portugal, a parish in the ...
forms of
Durga Durga ( sa, दुर्गा, ) is a major Hindu goddess, worshipped as a principal aspect of the mother goddess Mahadevi. She is associated with protection, strength, motherhood, destruction, and wars. Durga's legend centres around c ...
. *
Navaratna ''Navaratna'' ( sa, नवरत्न) is a Sanskrit compound word meaning "nine gems" or "ratnas". Jewellery created in this style has important cultural significance in many southern, and south-eastern Asian cultures as a symbol of wealth, st ...
, meaning "nine jewels" may also refer to
Navaratnas Navaratnas (Sanskrit dvigu ''nava-ratna'', ) () or Nauratan was a term applied to a group of nine extraordinary people in an emperor's court in India. The well-known Nauratnas include the ones in the courts of the Hindu emperor Vikramaditya, th ...
– accomplished courtiers, Navratan – a kind of dish, or a form of
architecture Architecture is the art and technique of designing and building, as distinguished from the skills associated with construction. It is both the process and the product of sketching, conceiving, planning, designing, and constructing building ...
. *In
Indian aesthetics Indian art evolved with an emphasis on inducing special spiritual or philosophical states in the audience, or with representing them symbolically. Rasas in the performing arts The theory of rasas still forms the aesthetic underpinning of a ...
, there are nine kinds of Rasa.


Chinese culture

*Nine (
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 ...
jiǔ) is considered a good number in Chinese culture because it sounds the same as the word "long-lasting" (
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 ...
jiǔ). *Nine is strongly associated with the
Chinese dragon The Chinese dragon, also known as ''loong'', ''long'' or ''lung'', is a legendary creature in Chinese mythology, Chinese folklore, and Chinese culture at large. Chinese dragons have many animal-like forms such as turtles and fish, but are most ...
, a symbol of magic and power. There are nine forms of the dragon, it is described in terms of nine attributes, and it has nine children. It has 117 scales – 81 yang (masculine, heavenly) and 36
yin Yin may refer to: *the dark force in the yin and yang from traditional Chinese philosophy and medicine *Yīn (surname) (), a Chinese surname *Yǐn (surname) (), a Chinese surname *Shang dynasty, also known as the Yin dynasty **Yinxu or Yin, the S ...
(feminine, earthly). All three numbers are multiples of 9 (, , ) as well as having the same
digital root The digital root (also repeated digital sum) of a natural number in a given radix is the (single digit) value obtained by an iterative process of summing digits, on each iteration using the result from the previous iteration to compute a digit su ...
of 9. *The dragon often symbolizes the
Emperor An emperor (from la, imperator, via fro, empereor) is a monarch, and usually the sovereignty, sovereign ruler of an empire or another type of imperial realm. Empress, the female equivalent, may indicate an emperor's wife (empress consort), ...
, and the number nine can be found in many ornaments in the
Forbidden City The Forbidden City () is a palace complex in Dongcheng District, Beijing, China, at the center of the Imperial City of Beijing. It is surrounded by numerous opulent imperial gardens and temples including the Zhongshan Park, the sacrifi ...
. *The circular altar platform (''Earthly Mount'') of the
Temple of Heaven The Temple of Heaven () is a complex of imperial religious buildings situated in the southeastern part of central Beijing. The complex was visited by the Emperors of the Ming and Qing dynasties for annual ceremonies of prayer to Heaven for ...
has one circular marble plate in the center, surrounded by a ring of nine plates, then by a ring of 18 plates, and so on, for a total of nine rings, with the outermost having *The name of the area called '' Kowloon'' in Hong Kong literally means: ''nine
dragons A dragon is a reptilian legendary creature that appears in the folklore of many cultures worldwide. Beliefs about dragons vary considerably through regions, but dragons in western cultures since the High Middle Ages have often been depicted as ...
''. *The nine-dotted line () delimits certain island claims by China in the South China Sea. *The
nine-rank system The nine-rank system, also known as the nine-grade controller system, was used to categorize and classify government officials in Imperial China. Created in the state of Cao Wei during the Three Kingdoms, it was used until the Song dynasty, and si ...
was a civil service nomination system used during certain Chinese dynasties. *9 Points of the
Heart The heart is a muscular organ in most animals. This organ pumps blood through the blood vessels of the circulatory system. The pumped blood carries oxygen and nutrients to the body, while carrying metabolic waste such as carbon dioxide to t ...
( Heal) / Heart Master (
Immortality Immortality is the concept of eternal life. Some modern species may possess biological immortality. Some scientists, futurists, and philosophers have theorized about the immortality of the human body, with some suggesting that human immorta ...
) Channels in
Traditional Chinese Medicine Traditional Chinese medicine (TCM) is an alternative medical practice drawn from traditional medicine in China. It has been described as "fraught with pseudoscience", with the majority of its treatments having no logical mechanism of acti ...
.


Ancient Egypt

*The
nine bows The Nine Bows is a visual representation in Ancient Egyptian art of foreigners or others. Besides the nine bows, there were no other generic representations of foreigners. Due to its ability to stand in for any nine enemies to Ancient Egypt, the ...
is a term used in Ancient Egypt to represent the traditional enemies of Egypt. *The Ennead is a group of nine Egyptian deities, who, in some versions of the Osiris myth, judged whether Horus or Set should inherit Egypt.


European culture

*The
Nine Worthies The Nine Worthies are nine historical, scriptural, and legendary men of distinction who personify the ideals of chivalry established in the Middle Ages, whose lives were deemed a valuable study for aspirants to chivalric status. All were commonly ...
are nine historical, or semi-legendary figures who, in the Middle Ages, were believed to personify the ideals of chivalry. *In Norse mythology, the universe is divided into
nine worlds Norse cosmology is the study of the cosmos (cosmology) as perceived by the ancient North Germanic peoples. The topic encompasses concepts from Norse mythology, such as notions of time and space, cosmogony, personifications, anthropogeny, and escha ...
which are all connected by the world tree
Yggdrasil Yggdrasil (from Old Norse ), in Norse cosmology, is an immense and central sacred tree. Around it exists all else, including the Nine Worlds. Yggdrasil is attested in the ''Poetic Edda'' compiled in the 13th century from earlier traditional ...
*In Norse mythology as well, the number nine is associated with Odin, as that is how many days he hung from the world tree
Yggdrasil Yggdrasil (from Old Norse ), in Norse cosmology, is an immense and central sacred tree. Around it exists all else, including the Nine Worlds. Yggdrasil is attested in the ''Poetic Edda'' compiled in the 13th century from earlier traditional ...
before attaining knowledge of the
runes Runes are the 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, and for specialised ...
.


Greek mythology

*The nine
Muse In ancient Greek religion and mythology, the Muses ( grc, Μοῦσαι, Moûsai, el, Μούσες, Múses) are the inspirational goddesses of literature, science, and the arts. They were considered the source of the knowledge embodied in the ...
s in Greek mythology are
Calliope In Greek mythology, Calliope ( ; grc, Καλλιόπη, Kalliópē, beautiful-voiced) is the Muse who presides over eloquence and epic poetry; so called from the ecstatic harmony of her voice. Hesiod and Ovid called her the "Chief of all Muse ...
(epic poetry),
Clio In Greek mythology, Clio ( , ; el, Κλειώ), also spelled Kleio, is the muse of history, or in a few mythological accounts, the muse of lyre playing. Etymology Clio's name is etymologically derived from the Greek root κλέω/κλεί ...
(history), Erato (erotic poetry), Euterpe (lyric poetry), Melpomene (tragedy), Polyhymnia (song),
Terpsichore In Greek mythology, Terpsichore (; grc-gre, Τερψιχόρη, "delight in dancing") is one of the nine Muses and goddess of dance and chorus. She lends her name to the word "terpsichorean" which means "of or relating to dance". Appearance ...
(dance), Thalia (comedy), and
Urania Urania ( ; grc, , Ouranía; modern Greek shortened name ''Ránia''; meaning "heavenly" or "of heaven") was, in Greek mythology, the muse of astronomy, and in later times, of Christian poetry. Urania is the goddess of astronomy and stars, he ...
(astronomy). *It takes nine days (for an anvil) to fall from heaven to earth, and nine more to fall from earth to
Tartarus In Greek mythology, Tartarus (; grc, , }) is the deep abyss that is used as a dungeon of torment and suffering for the wicked and as the prison for the Titans. Tartarus is the place where, according to Plato's ''Gorgias'' (), souls are judg ...
. *
Leto In ancient Greek mythology and religion, Leto (; grc-gre, Λητώ , ''Lētṓ'', or , ''Lātṓ'' in Doric Greek) is a goddess and the mother of Apollo, the god of music, and Artemis, the goddess of the hunt.Hesiod, ''Theogony'404–409/ref> ...
labored for nine days and nine nights for
Apollo Apollo, grc, Ἀπόλλωνος, Apóllōnos, label=genitive , ; , grc-dor, Ἀπέλλων, Apéllōn, ; grc, Ἀπείλων, Apeílōn, label= Arcadocypriot Greek, ; grc-aeo, Ἄπλουν, Áploun, la, Apollō, la, Apollinis, label ...
, according to the Homeric Hymn to Delian Apollo.


Mesoamerican mythology

* The
Lords of the Night In Mesoamerican mythology the Lords of the Night ( nci, Yoalteuctin) are a set of nine gods who each ruled over every ninth night forming a calendrical cycle. Each lord was associated with a particular fortune, bad or good, that was an omen for ...
, is a group of nine deities who each ruled over every ninth night forming a calendrical cycle


Aztec mythology

* Mictlan the underworld in Aztec mythology, consists of nine levels.


Mayan mythology

* The Mayan underworld
Xibalba (), roughly translated as "place of fright", is the name of the underworld (or quc, Mitnal) in Maya mythology, ruled by the Maya death gods and their helpers. In 16th-century Verapaz, the entrance to Xibalba was traditionally held to be a ...
consists of nine levels. * El Castillo the Mayan step-pyramid in Chichén Itzá, consists of nine steps. It is said that this was done to represent the nine levels of
Xibalba (), roughly translated as "place of fright", is the name of the underworld (or quc, Mitnal) in Maya mythology, ruled by the Maya death gods and their helpers. In 16th-century Verapaz, the entrance to Xibalba was traditionally held to be a ...
.


Anthropology


Idioms

*"to go the whole nine yards-" *"A cat-o'-nine-tails suggests perfect punishment and atonement." –
Robert Ripley LeRoy Robert Ripley (February 22, 1890 – May 27, 1949) was an American cartoonist, entrepreneur, and amateur anthropologist, who is known for creating the ''Ripley's Believe It or Not!'' newspaper panel series, television show, and radio show, ...
. *"A cat has nine lives" *"to be on cloud nine" *"A stitch in time saves nine" *"found true 9 out of 10 times" *"possession is nine tenths of the law" *The word "K-9" pronounces the same as ''canine'' and is used in many US police departments to denote the police dog unit. Despite not sounding like the translation of the word ''canine'' in other languages, many police and military units around the world use the same designation. *Someone dressed "to the nines" is dressed up as much as they can be. *In North American
urban culture Urban culture is the culture of towns and cities. The defining theme is the presence of a great number of very different people in a very limited space - most of them are strangers to each other but still try to be polite to each other more times ...
, "nine" is a slang word for a 9mm pistol or homicide, the latter from the Illinois Criminal Code for homicide.


Society

*''
The 9 on Yahoo! ''The 9'' was a daily video compilation show, or vlog, on Yahoo! featuring the nine top web finds of the day. ''The 9'' was launched on Yahoo!'s homepage (and Yahoo! TV) on July 10, 2006. The show, hosted by Maria Sansone, followed a similar forma ...
'', hosted by
Maria Sansone Maria Grace Sansone (born February 26, 1981) is an American television personality. Sansone is the former co-anchor of ''Good Day LA'' on KTTV Fox 11 in Los Angeles until January 2017 and is a former field reporter for WNBC 4 New York, appearin ...
, was a daily video compilation show, or vlog, on Yahoo! featuring the nine top "web finds" of the day. *Nine justices sit on the
United States Supreme Court The Supreme Court of the United States (SCOTUS) is the highest court in the federal judiciary of the United States. It has ultimate appellate jurisdiction over all U.S. federal court cases, and over state court cases that involve a point o ...
. *Nine justices sit on the Supreme Court of Canada.


Technique

*
Stanine Stanine (STAndard NINE) is a method of scaling test scores on a nine-point standard scale with a mean of five and a standard deviation of two. Some web sources attribute stanines to the U.S. Army Air Forces during World War II. Psychometric lege ...
s, a method of scaling test scores, range from 1 to 9. *There are 9
square feet The square foot (plural square feet; abbreviated sq. ft, sf, or ft2; also denoted by '2) is an imperial unit and U.S. customary unit (non- SI, non-metric) of area, used mainly in the United States and partially in Canada, the United Kingdom, Bang ...
in a
square yard The square yard (Northern India: gaj, Pakistan: gaz) is an imperial unit and U.S. customary unit of area. It is in widespread use in most of the English-speaking world, particularly the United States, United Kingdom, Canada, Pakistan and India. ...
.


Pseudoscience

* In Pythagorean numerology the number 9 symbolizes the end of one cycle and the beginning of another.


Literature

*There are nine circles of Hell in Dante's ''
Divine Comedy The ''Divine Comedy'' ( it, Divina Commedia ) is an Italian narrative poem by Dante Alighieri, begun 1308 and completed in around 1321, shortly before the author's death. It is widely considered the pre-eminent work in Italian literature ...
''. *The Nine Bright Shiners, characters in Garth Nix's Old Kingdom trilogy. ''The Nine Bright Shiners'' was a 1930s book of poems by Anne Ridler and a 1988 fiction book by Anthea Fraser; the name derives from "a very curious old semi-pagan, semi-Christian" song. *'' The Nine Tailors'' is a 1934
mystery novel Mystery is a fiction genre where the nature of an event, usually a murder or other crime, remains mysterious until the end of the story. Often within a closed circle of suspects, each suspect is usually provided with a credible motive and a re ...
by British writer
Dorothy L. Sayers Dorothy Leigh Sayers (; 13 June 1893 – 17 December 1957) was an English crime writer and poet. She was also a student of classical and modern languages. She is best known for her mysteries, a series of novels and short stories set between th ...
, her ninth featuring sleuth
Lord Peter Wimsey Lord Peter Death Bredon Wimsey (later 17th Duke of Denver) is the fictional protagonist in a series of detective novels and short stories by Dorothy L. Sayers (and their continuation by Jill Paton Walsh). A dilettante who solves mysteries fo ...
. *
Nine Unknown Men ''The Nine Unknown'' is a 1923 novel by Talbot Mundy. Originally serialised in ''Adventure'' magazine, it concerns the Nine Unknown Men, a secret society founded to preserve and develop knowledge that would be dangerous to humanity if it fell in ...
are, in occult legend, the custodians of the sciences of the world since ancient times. *In
J. R. R. Tolkien John Ronald Reuel Tolkien (, ; 3 January 1892 – 2 September 1973) was an English writer and philologist. He was the author of the high fantasy works ''The Hobbit'' and ''The Lord of the Rings''. From 1925 to 1945, Tolkien was the Rawlins ...
's
Middle-earth Middle-earth is the fictional setting of much of the English writer J. R. R. Tolkien's fantasy. The term is equivalent to the '' Miðgarðr'' of Norse mythology and ''Middangeard'' in Old English works, including ''Beowulf''. Middle-earth is ...
, there are nine rings of power given to men, and consequently, nine ringwraiths. Additionally,
The Fellowship of the Ring ''The Fellowship of the Ring'' is the first of three volumes of the epic novel ''The Lord of the Rings'' by the English author J. R. R. Tolkien. It is followed by '' The Two Towers'' and ''The Return of the King''. It takes place in the ficti ...
consists of nine companions. *In ''
Lorien Legacies ''Lorien Legacies'' is a series of young adult science fiction books, written by James Frey, Jobie Hughes, and formerly, Greg Boose, under the collective pseudonym Pittacus Lore. Lorien Legacies ''I am Number Four'' The first book of The ...
'' there are nine Garde sent to Earth. *Number Nine is a character in ''
Lorien Legacies ''Lorien Legacies'' is a series of young adult science fiction books, written by James Frey, Jobie Hughes, and formerly, Greg Boose, under the collective pseudonym Pittacus Lore. Lorien Legacies ''I am Number Four'' The first book of The ...
''. *In the series '' A Song of Ice and Fire'', there are nine regions of Westeros (the Crownlands, the North, the Riverlands, the Westerlands, the Reach, the Stormlands, the Vale of Arryn, the Iron Islands and Dorne). Additionally, there is a group of nine city-states in western Essos known collectively as the Free Cities (Braavos, Lorath, Lys, Myr, Norvos, Pentos, Qohor, Tyrosh and Volantis). *In ''
The Wheel of Time ''The Wheel of Time'' is a series of high fantasy novels by American author Robert Jordan, with Brandon Sanderson as a co-author for the final three novels. Originally planned as a six-book series, ''The Wheel of Time'' spans 14 volumes, in ad ...
'' series, Daughter of the Nine Moons is the title given to the heir to the throne of Seanchan, and the Court of the Nine Moons serves as the throne room of the Seanchan rulers themselves. Additionally, the nation of Illian is partially governed by a body known as the Council of Nine, and the flag of Illian displays nine golden bees on it. Furthermore, in the Age of Legends, the Nine Rods of Dominion were nine regional governors who administered individual areas of the world under the ruling world government.


Organizations

*Divine Nine – The
National Pan-Hellenic Council The National Pan-Hellenic Council (NPHC) is a collaborative umbrella council composed of historically African American fraternities and sororities also referred to as Black Greek Letter Organizations (BGLOs). The NPHC was formed as a permanent ...
(NPHC) is a collaborative organization of nine historically African American, international Greek-lettered fraternities and sororities.


Places and thoroughfares

* List of highways numbered 9 * Ninth Avenue is a major avenue in Manhattan. *
South Africa South Africa, officially the Republic of South Africa (RSA), is the Southern Africa, southernmost country in Africa. It is bounded to the south by of coastline that stretch along the Atlantic Ocean, South Atlantic and Indian Oceans; to the ...
has 9 provinces * Negeri Sembilan, a
Malaysia Malaysia ( ; ) is a country in Southeast Asia. The federation, federal constitutional monarchy consists of States and federal territories of Malaysia, thirteen states and three federal territories, separated by the South China Sea into two r ...
n
state State may refer to: Arts, entertainment, and media Literature * ''State Magazine'', a monthly magazine published by the U.S. Department of State * ''The State'' (newspaper), a daily newspaper in Columbia, South Carolina, United States * ''Our S ...
located in
Peninsular Malaysia Peninsular Malaysia ( ms, Semenanjung Malaysia; Jawi: سمننجڠ مليسيا), or the States of Malaya ( ms, Negeri-negeri Tanah Melayu; Jawi: نڬري-نڬري تانه ملايو), also known as West Malaysia or the Malaysian Peninsula, ...
, is named as such as it was historically a confederation of nine ( ms, sembilan) settlements ('' nagari'') of the
Minangkabau Minangkabau may refer to: * Minangkabau culture, culture of the Minangkabau people * Minangkabau Culture Documentation and Information Center * Minangkabau Express, an airport rail link service serving Minangkabau International Airport (''see belo ...
migrated from
West Sumatra West Sumatra ( id, Sumatra Barat) is a province of Indonesia. It is located on the west coast of the island of Sumatra and includes the Mentawai Islands off that coast. The province has an area of , with a population of 5,534,472 at the 2020 cen ...
.


Religion and philosophy

*Nine, as the highest single-digit number (in base ten), symbolizes completeness in the
Baháʼí Faith The Baháʼí Faith is a religion founded in the 19th century that teaches the essential worth of all religions and the unity of all people. Established by Baháʼu'lláh in the 19th century, it initially developed in Iran and parts of the ...
. In addition, the word Baháʼ in the Abjad notation has a value of 9, and a 9-pointed star is used to symbolize the religion. *The number 9 is revered in Hinduism and considered a complete, perfected and divine number because it represents the end of a cycle in the decimal system, which originated from the Indian subcontinent as early as
3000 BC The 30th century BC was a century that lasted from the year 3000 BC to 2901 BC. Events * Before 3000 BC: An image of a deity (detail from a cong) recovered from Tomb 12 in Fanshan, Yuyao, Zhejiang, is made during the Neolithic period by the Li ...
. *In Buddhism,
Gautama Buddha Siddhartha Gautama, most commonly referred to as the Buddha, was a wandering ascetic and religious teacher who lived in South Asia during the 6th or 5th century BCE and founded Buddhism. According to Buddhist tradition, he was born in Lu ...
was believed to have nine virtues, which he was (1) Accomplished, (2) Perfectly Enlightened, (3) Endowed with knowledge and Conduct or Practice, (4) Well-gone or Well-spoken, (5) the Knower of worlds, (6) the Guide Unsurpassed of men to be tamed, (7) the Teacher of gods and men, (8) Enlightened, and (9) Blessed. *Important Buddhist rituals usually involve nine monks. *The first nine days of the
Hebrew month The Hebrew calendar ( he, הַלּוּחַ הָעִבְרִי, translit=HaLuah HaIvri), also called the Jewish calendar, is a lunisolar calendar used today for Jewish religious observance, and as an official calendar of the state of Israel. I ...
of Av are collectively known as "The Nine Days" (''Tisha HaYamim''), and are a period of semi-mourning leading up to
Tisha B'Av Tisha B'Av ( he, תִּשְׁעָה בְּאָב ''Tīšʿā Bəʾāv''; , ) is an annual 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-Babylonian E ...
, the ninth day of Av on which both Temples in Jerusalem were destroyed. *Nine is a significant number in Norse Mythology. Odin hung himself on an ash tree for nine days to learn the runes. *The Fourth Way Enneagram is one system of knowledge which shows the correspondence between the 9 integers and the circle. *In the
Christian angelic hierarchy In Christianity, angels are the agents of God. Various works of Christian theology have devised hierarchies of angelic beings. The most influential Christian angelic hierarchy was put forward around the turn of the 6th century AD by Pseudo-Di ...
there are 9 choirs of angels. * Ramadan, the month of fasting and prayer, is the ninth month of the
Islamic calendar The Hijri calendar ( ar, ٱلتَّقْوِيم ٱلْهِجْرِيّ, translit=al-taqwīm al-hijrī), also known in English as the Muslim calendar and Islamic calendar, is a lunar calendar consisting of 12 lunar months in a year of 354 ...
. *Tian's Trigram Number, of Feng Shui, in
Taoism Taoism (, ) or Daoism () refers to either a school of philosophical thought (道家; ''daojia'') or to a religion (道教; ''daojiao''), both of which share ideas and concepts of Chinese origin and emphasize living in harmony with the '' Ta ...
. *In Christianity there are nine
Fruit of the Holy Spirit The Fruit of the Holy Spirit (sometimes, incorrectly, referred to as the Fruits of the Holy Spirit) is a biblical term that sums up nine attributes of a person or community living in accord with the Holy Spirit, according to chapter 5 of the Epi ...
which followers are expected to have:
love Love encompasses a range of strong and positive emotional and mental states, from the most sublime virtue or good habit, the deepest interpersonal affection, to the simplest pleasure. An example of this range of meanings is that the love o ...
,
joy The word joy refers to the emotion evoked by well-being, success, or good fortune, and is typically associated with feelings of intense, long lasting happiness. Dictionary definitions Dictionary definitions of joy typically include a sense of ...
,
peace Peace is a concept of societal friendship and harmony in the absence of hostility and violence. In a social sense, peace is commonly used to mean a lack of conflict (such as war) and freedom from fear of violence between individuals or groups. ...
,
patience (or forbearance) is the ability to endure difficult circumstances. Patience may involve perseverance in the face of delay; tolerance of provocation without responding in disrespect/anger; or forbearance when under strain, especially when face ...
, kindness, goodness,
faithfulness Faithfulness is the concept of unfailingly remaining loyal to someone or something, and putting that loyalty into consistent practice regardless of extenuating circumstances. It may be exhibited by a husband or wife who does not engage in sexua ...
,
gentleness Gentleness is a personal quality which can be part of one's character. It consists in kindness, consideration and amiability. Aristotle used it in a technical sense as the virtue that strikes the mean with regard to anger: being too quick to anger ...
, and
self-control Self-control, an aspect of inhibitory control, is the ability to regulate one's emotions, thoughts, and behavior in the face of temptations and impulses. As an executive function, it is a cognitive process that is necessary for regulating one' ...
. *The Bible recorded that Christ died at the 9th hour of the day (3 pm).


Science


Astronomy

*Before 2006 (when Pluto was officially designated as a non-planet), there were nine
planet A planet is a large, rounded astronomical body that is neither a star nor its remnant. The best available theory of planet formation is the nebular hypothesis, which posits that an interstellar cloud collapses out of a nebula to create a you ...
s in the
Solar System The Solar System Capitalization of the name varies. The International Astronomical Union, the authoritative body regarding astronomical nomenclature, specifies capitalizing the names of all individual astronomical objects but uses mixed "Solar ...
. *
Messier object The Messier objects are a set of 110 astronomical objects catalogued by the French astronomer Charles Messier in his ''Catalogue des Nébuleuses et des Amas d'Étoiles'' (''Catalogue of Nebulae and Star Clusters''). Because Messier was only in ...
M9 is a magnitude 9.0
globular cluster A globular cluster is a spheroidal conglomeration of stars. Globular clusters are bound together by gravity, with a higher concentration of stars towards their centers. They can contain anywhere from tens of thousands to many millions of membe ...
in the constellation
Ophiuchus Ophiuchus () is a large constellation straddling the celestial equator. Its name comes from the Ancient Greek (), meaning "serpent-bearer", and it is commonly represented as a man grasping a snake. The serpent is represented by the constella ...
. *The New General Cataloguebr>object
NGC 9 NGC 9 is a spiral galaxy about 140 million light-years away in the Pegasus Pegasus ( grc-gre, Πήγασος, Pḗgasos; la, Pegasus, Pegasos) is one of the best known creatures in Greek mythology. He is a winged divine stallion usuall ...
, a spiral galaxy in the constellation Pegasus.


Chemistry

*The purity of chemicals (see
Nine (purity) Nines are an informal, logarithmic notation for proportions very near to one, or equivalently percentages very near 100%. Their common uses include grading the purity of materials. Put simply, "nines" are the number of consecutive nines in a perce ...
). *Nine 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 fluorine.


Physiology

A human
pregnancy Pregnancy is the time during which one or more offspring develops (gestation, gestates) inside a woman, woman's uterus (womb). A multiple birth, multiple pregnancy involves more than one offspring, such as with twins. Pregnancy usually occur ...
normally lasts nine months, the basis of Naegele's rule.


Psychology

Common terminal digit in psychological pricing.


Sports

* Nine-ball is the standard professional pocket
billiards Cue sports are a wide variety of games of skill played with a cue, which is used to strike billiard balls and thereby cause them to move around a cloth-covered table bounded by elastic bumpers known as . There are three major subdivisions ...
variant played in the United States. *In
association football Association football, more commonly known as football or soccer, is a team sport played between two teams of 11 players who primarily use their feet to propel the ball around a rectangular field called a pitch. The objective of the game is ...
(soccer), the centre-forward/striker traditionally (since at least the fifties) wears the number 9 shirt. *In
baseball Baseball is a bat-and-ball sport played between two teams of nine players each, taking turns batting and fielding. The game occurs over the course of several plays, with each play generally beginning when a player on the fielding t ...
: **There are nine players on the field including the pitcher. **There are nine innings in a standard game. **9 represents the
right fielder A right fielder, abbreviated RF, is the outfielder in baseball or softball who plays defense in right field. Right field is the area of the outfield to the right of a person standing at home plate and facing towards the pitcher's mound. In the ...
's position. **''NINE: A Journal of Baseball History and Culture'', published by the
University of Nebraska Press The University of Nebraska Press, also known as UNP, was founded in 1941 and is an academic publisher of scholarly and general-interest books. The press is under the auspices of the University of Nebraska–Lincoln, the main campus of the Unive ...
*In
rugby league Rugby league football, commonly known as just rugby league and sometimes football, footy, rugby or league, is a full-contact sport played by two teams of thirteen players on a rectangular field measuring 68 metres (75 yards) wide and 11 ...
, the jersey number assigned to the hooker in most competitions. (An exception is the Super League, which uses static squad numbering.) *In
rugby union Rugby union, commonly known simply as rugby, is a close-contact team sport that originated at Rugby School in the first half of the 19th century. One of the two codes of rugby football, it is based on running with the ball in hand. In it ...
, the number worn by the starting scrum-half.


Technology

*
ISO 9 ISO 9 is an international standard establishing a system for the transliteration into Latin characters of Cyrillic characters constituting the alphabets of many Slavic and non-Slavic languages. Published on February 23, 1995 by the Internatio ...
is the
ISO ISO is the most common abbreviation for the International Organization for Standardization. ISO or Iso may also refer to: Business and finance * Iso (supermarket), a chain of Danish supermarkets incorporated into the SuperBest chain in 2007 * Iso ...
's standard for the transliteration of Cyrillic characters into
Latin Latin (, or , ) is a classical language belonging to the Italic branch of the Indo-European languages. Latin was originally a dialect spoken in the lower Tiber area (then known as Latium) around present-day Rome, but through the power of the ...
characters *In the Rich Text Format specification, 9 is the language code for the
English language English is a West Germanic language of the Indo-European language family, with its earliest forms spoken by the inhabitants of early medieval England. It is named after the Angles, one of the ancient Germanic peoples that migrated to the ...
. All codes for regional variants of English are congruent to 9 mod 256. *
The9 The9 Ltd. () is a Shanghai-based online game operator which had the exclusive licence to operate and distribute World of Warcraft in China (launched in June 2005, it has since become the largest online game), a licence it secured after successf ...
Limited (owner o
the9.com
is a company in the video-game industry, including former ties to the extremely popular MMORPG
World of Warcraft ''World of Warcraft'' (''WoW'') is a massively multiplayer online role-playing game (MMORPG) released in 2004 by Blizzard Entertainment. Set in the ''Warcraft'' fantasy universe, ''World of Warcraft'' takes place within the world of Azeroth ...
.


Music

*"
Revolution 9 "Revolution 9" is a sound collage from the Beatles' 1968 self-titled double album (also known as the "White Album"). The composition, credited to Lennon–McCartney, was created primarily by John Lennon with assistance from Yoko Ono and George ...
", a sound collage which appears on The Beatles' eponymous 1968 album ''The Beatles'' (aka ''The White Album''), prominently features a loop of a man's voice repeating the phrase "Number nine". *There are 9 semitones in a Major 6th interval in music. *There was a superstition among some notable classical music composers that they would die after completing their ninth symphony. Some composers who died after composing their ninth symphony include
Ludwig van Beethoven Ludwig van Beethoven (baptised 17 December 177026 March 1827) was a German composer and pianist. Beethoven remains one of the most admired composers in the history of Western music; his works rank amongst the most performed of the classic ...
, Anton Bruckner,
Antonin Dvorak Antonin may refer to: People * Antonin (name) Places ;Poland * Antonin, Jarocin County, Greater Poland Voivodeship * Antonin, Kalisz County, Greater Poland Voivodeship * Antonin, Oborniki County, Greater Poland Voivodeship * Antonin, Ostrów ...
and Gustav Mahler.


See also

*
9 (disambiguation) 9 is a number, numeral, and glyph. 9 or nine may also refer to: Dates * AD 9, the ninth year of the AD era * 9 BC, the ninth year before the AD era * 9, numerical symbol for the month of September Places * Nine, Portugal, a parish in the ...
* 0.999... * Cloud Nine * List of highways numbered 9


References


Further reading

*Cecil Balmond, "Number 9, the search for the sigma code" 1998, Prestel 2008, , {{DEFAULTSORT:9 (Number) Integers 9 (number) Superstitions about numbers