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 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 typefaces, in typefaces with text figures the character usually has a descender, as, for example, in TextFigs196

. 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 of the form ''p''² and first that is odd, with all subsequent squares of this form odd as well. By Mihăilescu's theorem, 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. MotzkinChords4

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. 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

3

magic square made of nine cells, with a magic constant of 15; there are no

2

2

magic squares with four cells. Meanwhile, a

9

9

magic square has a magic constant of 369. A polygon 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. 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 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: *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 solids: 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 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 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, 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

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 digit 9 is called "Niner". *Five-digit produce PLU codes that begin with 9 are organic.

Culture and mythology

Indian culture

Nine is a number that appears often in Indian culture 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,

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,

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 is a nine-day festival dedicated to the

forms of Durga. * Navaratna, meaning "nine jewels" may also refer to Navaratnas – 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" (

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

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 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 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) 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 The Ennead or Great Ennead was a group of nine deities in Egyptian mythology worshipped at Heliopolis: the sun god Atum; his children Shu and Tefnut; their children Geb and Nut; and their children Osiris, Isis, Set, and Nephthys. The Ennead ...

is a group of nine Egyptian deities, who, in some versions of the

Osiris myth The Osiris myth is the most elaborate and influential story in ancient Egyptian mythology. It concerns the murder of the god Osiris, a primeval king of Egypt, and its consequences. Osiris's murderer, his brother Set, usurps his throne. Meanwhile, ...

, judged whether

Horus Horus or Heru, Hor, Har in Ancient Egyptian, is one of the most significant ancient Egyptian deities who served many functions, most notably as god of kingship and the sky. He was worshipped from at least the late prehistoric Egypt until the P ...

Set Set, The Set, SET or SETS may refer to: Science, technology, and mathematics Mathematics *Set (mathematics), a collection of elements *Category of sets, the category whose objects and morphisms are sets and total functions, respectively Electro ...

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 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 ...

, 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 e ...

which are all connected by the

world tree The world tree is a motif present in several religions and mythologies, particularly Indo-European religions, Siberian religions, and Native American religions. The world tree is represented as a colossal tree which supports the heavens, thereb ...

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 s ...

*In

as well, the number nine is associated with

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 ...

, as that is how many days he hung from the

before attaining knowledge of 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 ...

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 Muses" ...

(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 In Greek mythology, Erato (; grc, Ἐρατώ) is one of the Greek Muses, which were inspirational goddesses of literature, science, and the arts. The name would mean "desired" or "lovely", if derived from the same root as Eros, as Apollonius o ...

(erotic poetry),

Euterpe Euterpe (; el, Εὐτέρπη, lit=rejoicing well' or 'delight , from grc, εὖ, eû, well + el, τέρπειν, térpein, to please) was one of the Muses in Greek mythology, presiding over music. In late Classical times, she was named muse ...

(lyric poetry),

Melpomene In Greek mythology, Melpomene (; grc, Μελπομένη, Melpoménē, to sing' or 'the one that is melodious), initially the muse of chorus, eventually became the muse of tragedy, and is now best known in that association. Etymology Melp ...

(tragedy),

Polyhymnia Polyhymnia (; el, Πολυύμνια, lit=the one of many hymns), alternatively Polymnia (Πολύμνια), was, in Greek mythology, the Muse of sacred poetry, sacred hymn, dance and eloquence, as well as agriculture and pantomime. Etymology ...

(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 Thalia, Thalía, Thaleia or Thalian may refer to: People * Thalia (given name), including a list of people with the name * Thalía (born 1971), Mexican singer and actress Mythological and fictional characters * Thalia (Grace), one of the three ...

(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 Ancient Greek religion, religion, Leto (; grc-gre, Λητώ , ''Lētṓ'', or , ''Lātṓ'' in Ancient Greek dialects#Provenance, Doric Greek) is a goddess and the mother of Apollo, the god of music, and Artemis ...

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 c ...

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

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 A pistol is a handgun, more specifically one with the chamber integral to its gun barrel, though in common usage the two terms are often used interchangeably. The English word was introduced in , when early handguns were produced in Europe, an ...

homicide Homicide occurs when a person kills another person. A homicide requires only a volitional act or omission that causes the death of another, and thus a homicide may result from accidental, reckless, or negligent acts even if there is no inten ...

, 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 The Supreme Court of Canada (SCC; french: Cour suprême du Canada, CSC) is the Supreme court, highest court in the Court system of Canada, judicial system of Canada. It comprises List of Justices of the Supreme Court of Canada, nine justices, wh ...

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 Numerology (also known as arithmancy) is the belief in an occult, divine or mystical relationship between a number and one or more coinciding events. It is also the study of the numerical value, via an alphanumeric system, of the letters in ...

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 and ...

''. *The

Nine Bright Shiners The Old Kingdom, or Abhorsen in North America, is a fantasy series written by Australian author Garth Nix. It originated in 1995 with the novel ''Sabriel'' and has continued in the novels ''Lirael'' (2001), ''Abhorsen'' (2003) and ''Goldenhand'' ...

, characters in Garth Nix's

Old Kingdom trilogy The Old Kingdom, or Abhorsen in North America, is a fantasy series written by Australian author Garth Nix. It originated in 1995 with the novel ''Sabriel'' and has continued in the novels ''Lirael'' (2001), ''Abhorsen'' (2003) and ''Goldenhand'' ...

. ''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 ''The Nine Tailors'' is a 1934 mystery novel by the British writer Dorothy L. Sayers, her ninth featuring Lord Peter Wimsey. The story is set in the Lincolnshire Fens, and revolves around a group of bell-ringers at the local parish church. The b ...

'' 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 reas ...

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 philology, philologist. He was the author of the high fantasy works ''The Hobbit'' and ''The Lord of the Rings''. From 1925 to 1945, Tolkien was ...

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 t ...

, 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 fiction ...

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 L ...

'' there are nine Garde sent to Earth. *Number Nine is a character in ''

''. *In the series ''

A Song of Ice and Fire ''A Song of Ice and Fire'' is a series of epic fantasy novels by the American novelist and screenwriter George R. R. Martin. He began the first volume of the series, ''A Game of Thrones'', in 1991, and it was published in 1996. Martin, who init ...

'', 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 a ...

'' 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 Route 9, or Highway 9, may refer to: International * European route E09 * European route E009 Albania * SH-9 Road in Albania. Argentina * National Route 9 (Argentina), National Route 9 Australia New South Wales * A9 (Sydney) South Austra ...

* Ninth Avenue is a major avenue in Manhattan. *

South Africa South Africa, officially the Republic of South Africa (RSA), is the southernmost country in Africa. It is bounded to the south by of coastline that stretch along the South Atlantic and Indian Oceans; to the north by the neighbouring countri ...

has 9 provinces *

Negeri Sembilan Negeri Sembilan (, Negeri Sembilan Malay: ''Nogoghi Sombilan'', ''Nismilan'') is a state in Malaysia which lies on the western coast of Peninsular Malaysia. It borders Selangor on the north, Pahang in the east, and Malacca and Johor to the s ...

, 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 ...

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 Provinces of Indonesia, 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, ...

Religion and philosophy

*Nine, as the highest single-digit number (in

base ten 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 ...

), symbolizes completeness in the

Baháʼí Faith The Baháʼí Faith is a religion founded in the 19th century that teaches the Baháʼí Faith and the unity of religion, essential worth of all religions and Baháʼí Faith and the unity of humanity, the unity of all people. Established by ...

. 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 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 ...

system, which originated from the Indian subcontinent as early as 3000 BC. *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 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 ...

hung himself on an ash tree for nine days to learn the runes. *The

Fourth Way Enneagram The Fourth Way enneagram is a figure published in 1949 in ''In Search of the Miraculous'' by P.D. Ouspensky, and an integral part of the Fourth Way esoteric system associated with George Gurdjieff. The term " enneagram" derives from two Greek word ...

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 , type = islam , longtype = Religious , image = Ramadan montage.jpg , caption=From top, left to right: A crescent moon over Sarıçam, Turkey, marking the beginning of the Islamic month of Ramadan. Ramadan Quran reading in Bandar Torkaman, Iran. ...

, 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 or ...

. *Tian's Trigram Number, of Feng Shui, 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 ...

. *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 relationship, interpersonal affection, to the simplest pleasure. An example of this range of ...

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 faced ...

kindness Kindness is a type of behavior marked by acts of generosity, consideration, rendering assistant or concern for others, without expecting praise or reward in return. Kindness is a topic of interest in philosophy, religion, and psychology. Kin ...

, 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's b ...

. *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 SystemCapitalization 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 S ...

. *

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 int ...

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 Catalogue The ''New General Catalogue of Nebulae and Clusters of Stars'' (abbreviated NGC) is an astronomical catalogue of deep-sky objects compiled by John Louis Emil Dreyer in 1888. The NGC contains 7,840 objects, including galaxies, star clusters and ...

br>object

NGC 9 NGC 9 is a spiral galaxy about 140 million light-years away in the Pegasus constellation. It was discovered on 27 September 1865 by Otto Wilhelm von Struve Otto Wilhelm von Struve (May 7, 1819 (Julian calendar: April 25) – April 14, 1905) ...

, a

spiral galaxy Spiral galaxies form a class of galaxy originally described by Edwin Hubble in his 1936 work ''The Realm of the Nebulae''constellation A constellation is an area on the celestial sphere in which a group of visible stars forms Asterism (astronomy), a perceived pattern or outline, typically representing an animal, mythological subject, or inanimate object. The origins of the e ...

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 usually depicted as pure white in color. He was sired by Poseidon, in his role as hor ...

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 ...

fluorine Fluorine is a chemical element with the symbol F and atomic number 9. It is the lightest halogen and exists at standard conditions as a highly toxic, pale yellow diatomic gas. As the most electronegative reactive element, it is extremely reacti ...

Physiology

A human

pregnancy Pregnancy is the time during which one or more offspring develops ( gestates) inside a woman's uterus (womb). A multiple pregnancy involves more than one offspring, such as with twins. Pregnancy usually occurs by sexual intercourse, but ca ...

normally lasts nine months, the basis of Naegele's rule.

Psychology

Common terminal digit in psychological pricing.

Sports

Nine-ball Nine-ball (sometimes written 9-ball) is a discipline of the cue sport pool. The game's origins are traceable to the 1920s in the United States. It is played on a rectangular billiard table with at each of the four corners and in the middle of e ...

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 of ...

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 tea ...

: **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 Univer ...

*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 112 ...

, the jersey number assigned to the hooker in most competitions. (An exception 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.) *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 its m ...

, 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 International ...

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 , bg, кирилица , mk, кирилица , russian: кириллица , sr, ћирилица, uk, кирилиця , fam1 = Egyptian hieroglyphs , fam2 = Proto-Sinaitic , fam3 = Phoenician , fam4 = G ...

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 ) As an example, the following RTF code would be rendered as follows: This is some bold text. Character encoding A standard RTF file can only consist of 7-bit ASCII characters, but can use escape sequences to encode other characters. Th ...

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 is ...

. 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 A massively multiplayer online role-playing game (MMORPG) is a video game that combines aspects of a role-playing video game and a massively multiplayer online game. As in role-playing games (RPGs), the player assumes the role of a Player charac ...

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 In music from Western culture, a sixth is a musical interval encompassing six note letter names or staff positions (see Interval number for more details), and the major sixth is one of two commonly occurring sixths. It is qualified as ''major ...

interval in music. *There was a

superstition A superstition is any belief or practice considered by non-practitioners to be irrational or supernatural, attributed to fate or magic, perceived supernatural influence, or fear of that which is unknown. It is commonly applied to beliefs and ...

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 classical ...

Anton Bruckner Josef Anton Bruckner (; 4 September 182411 October 1896) was an Austrian composer, organist, and music theorist best known for his symphonies, masses, Te Deum and motets. The first are considered emblematic of the final stage of Austro-Germ ...

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 Gustav Mahler (; 7 July 1860 – 18 May 1911) was an Austro-Bohemian Romantic composer, and one of the leading conductors of his generation. As a composer he acted as a bridge between the 19th-century Austro-German tradition and the modernism ...