12 (twelve) is the natural number following 11 and preceding 13.
Twelve is the 3rd superior highly composite number, the 3rd colossally abundant number, the 5th highly composite number, and is divisible by the numbers from 1 to 4, and 6, a comparatively large number of divisors.
It is central to many systems of timekeeping, including the Western calendar and units of time of day, and frequently appears in the world's major religions.
Name Twelve is the largest number with a single-syllable name in English. Early Germanic numbers have been theorized to have been non-decimal: evidence includes the unusual phrasing of eleven and twelve, the former use of "hundred" to refer to groups of 120, and the presence of glosses such as "tentywise" or "ten-count" in medieval texts showing that writers could not presume their readers would normally understand them that way. Such uses gradually disappeared with the introduction of Arabic numerals during the 12th-century Renaissance.
Derived from Old English, and are first attested in the 10th-century Lindisfarne Gospels' Book of John. It has cognates in every Germanic language (e.g. German ), whose Proto-Germanic ancestor has been reconstructed as , from ("two") and suffix or of uncertain meaning. It is sometimes compared with the Lithuanian , although is used as the suffix for all numbers from 11 to 19 (analogous to "-teen"). Every other Indo-European language instead uses a form of "two"+"ten", such as the Latin . The usual ordinal form is "twelfth" but "dozenth" or "duodecimal" (from the Latin word) is also used in some contexts, particularly base-12 numeration. Similarly, a group of twelve things is usually a "dozen" but may also be referred to as a "dodecad" or "duodecad". The adjective referring to a group of twelve is "duodecuple".
As with eleven,Oxford English Dictionary, 1st ed. "eleven, adj. and n." Oxford University Press (Oxford), 1891. the earliest forms of twelve are often considered to be connected with Proto-Germanic or ("to leave"), with the implicit meaning that "two is left" after having already counted to ten.Oxford English Dictionary, 1st ed. "twelve, adj. and n." Oxford University Press (Oxford), 1916. The Lithuanian suffix is also considered to share a similar development. The suffix has also been connected with reconstructions of the Proto-Germanic for ten..
As mentioned above, 12 has its own name in Germanic languages such as English (dozen), Dutch (), German (), and Swedish (), all derived from Old French . It is a compound number in many other languages, e.g. Italian (but in Spanish and Portuguese, 16, and in French, 17 is the first compound number), Japanese 十二 jūni.
Written representation In prose writing, twelve, being the last single-syllable numeral, is sometimes taken as the last number to be written as a word, and 13 the first to be written using digits. This is not a binding rule, and in English language tradition, it is sometimes recommended to spell out numbers up to and including either nine, ten or twelve, or even ninety-nine or one hundred. Another system spells out all numbers written in one or two words (sixteen, twenty-seven, fifteen thousand, but 372 or 15,001). In German orthography, there used to be the widely followed (but unofficial) rule of spelling out numbers up to twelve (zwölf). The Duden (the German standard dictionary) mentions this rule as outdated.
In mathematics Properties 12 is the smallest abundant number because the sum of the proper divisors of 12, 16, is greater than 12. It is also the 3rd colossally abundant number. 12 is a semiperfect number because some of its proper divisors; 1, 2, 3, and 6; sum to 12.
12 is a highly composite number because it has 6 divisors, more than any number less than 12. It is the 3rd superior highly composite number. 12 is a refactorable number because it has 6 divisors and 12 is a multiple of 6. It is the smallest of two known sublime numbers, numbers that have a perfect number of divisors whose sum is also perfect.
12 is a Pell number because 17/12 is the closest approximation of the square root of 2 of any fraction with a denominator less than or equal to 12.
There are twelve Jacobian elliptic functions and twelve cubic distance-transitive graphs. Shapes A twelve-sided polygon is a dodecagon. In its regular form, it is the largest polygon that can uniformly tile the plane alongside other regular polygons, as with the truncated hexagonal tiling or the truncated trihexagonal tiling.
A regular dodecahedron has twelve pentagonal faces. Regular cubes and octahedrons both have 12 edges, while regular icosahedrons have 12 vertices.
The cubic close packing and hexagonal close packing, which are the two densest possible sphere packings in three-dimensional space (the Kepler conjecture, proved by Thomas Hales), both have each sphere touching twelve other spheres. Twelve is also the kissing number in three dimensions.
There are twelve complex apeirotopes in dimensions five and higher, which include van Oss polytopes in the form of complex -orthoplexes. There are also twelve paracompact hyperbolic Coxeter groups of uniform polytopes in five-dimensional space.
Bring's curve is a Riemann surface of genus four, with a domain that is a regular hyperbolic 20-sided icosagon. By the Gauss-Bonnet theorem, the area of this fundamental polygon is equal to . Functions Twelve is the smallest weight for which a cusp form exists. This cusp form is the discriminant whose Fourier coefficients are given by the Ramanujan -function and which is (up to a constant multiplier) the 24th power of the Dedekind eta function:
This fact is related to a constellation of interesting appearances of the number twelve in mathematics ranging from the fact that the abelianization of special linear group has twelve elements, to the value of the Riemann zeta function at being , which stems from the Ramanujan summation
Although the series is divergent, methods such as Ramanujan summation can assign finite values to divergent series.
List of basic calculations
Multiplication1234567891011121314151617181920212223242550100100012 × x1224364860728496108120132144156168180192204216228240252264276288300600120012000
Division1234567891011121314151612 ÷ x126432.421.1.51.1.21.10.0.0.80.75x ÷ 120.080.10.250.0.410.50.580.0.750.80.9111.081.11.251.
Exponentiation12345678910111212121441728207362488322985984358318084299816965159780352619173642247430083706888916100448256x1409653144116777216244140625217678233613841287201687194767362824295364811000000000000 31384283767218916100448256
In other bases
The duodecimal system (1210 [twelve] = 1012), which is the use of 12 as a division factor for many ancient and medieval weights and measures, including hours, probably originates from Mesopotamia.
Religion The number twelve carries religious, mythological and magical symbolism; since antiquity, the number has generally represented perfection, entirety, or cosmic order.
Judaism and Christianity
The number 12 is notable within the Hebrew Bible, and in Christianity:
Ishmaelthe first-born son of Abrahamhas 12 sons/princes (Genesis 25:16), and Jacob also has 12 sons, who are the progenitors of the Twelve Tribes of Israel."And it is thought that there is a special significance in the number twelve. It was typified, we know, by many things in the Old Testament; by the twelve sons of Jacob, by the twelve princes of the children of Israel, by the twelve fountains in Elim, by the twelve stones in Aaron's breast-plate, by the twelve loaves of the shew-bread, by the twelve spies sent by Moses, by the twelve stones of which the altar was made, by the twelve stones taken out of Jordan, by the twelve oxen which bare" P. Young, Daily readings for a year (1863), p. 150. This is reflected in Christian tradition, notably in the twelve Apostles. When Judas Iscariot is disgraced, a meeting is held (Acts) to add Saint Matthias to complete the number twelve once more.
The Old Testament contains Twelve Minor Prophets.
The Book of Revelation contains much numerical symbolism, and many of the numbers mentioned have 12 as a divisor. mentions a woman—interpreted as the people of Israel, the Church and the Virgin Mary—wearing a crown of twelve stars (representing each of the twelve tribes of Israel). Furthermore, there are 12,000 people sealed from each of the twelve tribes of Israel (the Tribe of Dan is omitted while Manasseh is mentioned), making a total of 144,000 (which is the square of 12 multiplied by a thousand). According to the New Testament, Jesus had twelve Apostles. The "Twelve Days of Christmas" count the interval between Christmas and Epiphany. Eastern Orthodoxy observes twelve Great Feasts.
Islam Twelve is mentioned a total of five times in four chapters (sura) of the Koran: 12 springs twice, once in The Heifer (al-Baqarah) 2:60, and once in The Heights (al-A'raf) 7:160 12 leaders in The Table Spread (al-Ma'idah) 5:12 12 tribes of Israel in The Heights (al-A'raf) 7:160 12 months in The Repentance (al-Tawbah) 9:36 Twelve Imams are the spiritual and political successors to the Islamic prophet Muhammad in the Twelver branch of Shia Islam. The hadith of the twelve successors is a widely reported prophecy, attributed to Prophet Muhammad, predicting that there would be twelve successors after him.
Sikhism There are considered to be 12 misls in the Sikh Conferacy.
Greek Mythology There are 12 Olympian gods in the ancient Greek pantheon.
Astrology Western astrology assigns people to one of 12 signs of the tropical zodiac, based on their date of birth. Hindu astrology is based on the 12 rāśi ("parts") of the sidereal zodiac.
Timekeeping The lunar year is 12 lunar months. Adding 11 or 12 days completes the solar year. Most calendar systems – solar or lunar – have twelve months in a year. The Chinese use a 12-year cycle for time-reckoning called Earthly Branches. There are twelve hours in a half day, numbered one to twelve for both the ante meridiem (a.m.) and the post meridiem (p.m.). 12:00 p.m. is midday or noon, and 12:00 a.m. is midnight. The basic units of time (60 seconds, 60 minutes, 24 hours) are evenly divisible by twelve into smaller units.
In numeral systems
Arabic Khmer Armenian Bangla Attic Greek Maya HebrewV20-Z1-Z1 Egyptian Indian and Nepali (Devanāgarī) Chinese and Japanese Tamil Roman and Etruscan Thai Chuvash Telugu and Kannada Urdu Ionian Greek Malayalam
In science Force 12 on the Beaufort wind force scale corresponds to the maximum wind speed of a hurricane.
In sports In both soccer and American football, the number 12 can be a symbolic reference to the fans because of the support they give to the 11 players on the field. Texas A&M University reserves the number 12 jersey for a walk-on player who represents the original "12th Man", a fan who was asked to play when the team's reserves were low in a college American football game in 1922. Similarly, Bayern Munich, Hammarby, Feyenoord, Atlético Mineiro, Flamengo, Seattle Seahawks, Portsmouth and Cork City do not allow field players to wear the number 12 on their jersey because it is reserved for their supporters. In rugby league, one of the starting second-row forwards wears the number 12 jersey in most competitions. An exception is in the Super League, which uses static squad numbering. In rugby union, one of the starting centres, most often but not always the inside centre, wears the 12 shirt.
In technology ASCII and Unicode code point for form feed.
Music Music theory Twelve is the number of pitch classes in an octave, not counting the duplicated (octave) pitch. Also, the total number of major keys, (not counting enharmonic equivalents) and the total number of minor keys (also not counting equivalents). This applies only to twelve tone equal temperament, the most common tuning used today in western influenced music.