Top Qs
Timeline
Chat
Perspective

12 (number)

Natural number From Wikipedia, the free encyclopedia

Remove ads

12 (twelve) is the natural number following 11 and preceding 13.

Quick Facts ← 11 12 13 →, Cardinal ...

Twelve is the 3rd superior highly composite number,[1] the 3rd colossally abundant number,[2] the 5th highly composite number, and is divisible by the numbers from 1 to 4, and 6, a large number of divisors comparatively.

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.

Remove ads

Name

Summarize
Perspective

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.[3][4][5] Such uses gradually disappeared with the introduction of Arabic numerals during the 12th-century Renaissance.

Derived from Old English, twelf and tuelf are first attested in the 10th-century Lindisfarne Gospels' Book of John.[note 1][7] It has cognates in every Germanic language (e.g. German zwölf), whose Proto-Germanic ancestor has been reconstructed as *twaliƀi..., from *twa ("two") and suffix *-lif- or *-liƀ- of uncertain meaning.[7] It is sometimes compared with the Lithuanian dvýlika, although -lika is used as the suffix for all numbers from 11 to 19 (analogous to "-teen").[7] Every other Indo-European language instead uses a form of "two"+"ten", such as the Latin duōdecim.[7] 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,[8] the earliest forms of twelve are often considered to be connected with Proto-Germanic *liƀan or *liƀan ("to leave"), with the implicit meaning that "two is left" after having already counted to ten.[7] The Lithuanian suffix is also considered to share a similar development.[7] The suffix *-lif- has also been connected with reconstructions of the Proto-Germanic for ten.[8][9]

As mentioned above, 12 has its own name in Germanic languages such as English (dozen), Dutch (dozijn), German (Dutzend), and Swedish (dussin), all derived from Old French dozaine. It is a compound number in many other languages, e.g. Italian dodici (but in Spanish and Portuguese, 16, and in French, 17 is the first compound number),[dubious discuss] Japanese 十二 jūni.[clarification needed]

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).[10] In German orthography, there used to be the widely followed (but unofficial) rule of spelling out numbers up to twelve (zwölf). The Duden[year needed] (the German standard dictionary) mentions this rule as outdated.

Remove ads

In mathematics

Summarize
Perspective

12 is a composite number, the smallest abundant number, a semiperfect number,[11] a highly composite number,[12] a refactorable number,[13] and a Pell number.[14] It is the smallest of two known sublime numbers, numbers that have a perfect number of divisors whose sum is also perfect.[15]

There are twelve Jacobian elliptic functions and twelve cubic distance-transitive graphs.

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.[16]

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.[17] 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.[18] By the Gauss-Bonnet theorem, the area of this fundamental polygon is equal to .

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

More information Multiplication ...
More information Division ...
More information Exponentiation ...

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.

Remove ads

Religion

Summarize
Perspective

The number twelve carries religious, mythological and magical symbolism; since antiquity, the number has generally represented perfection, entirety, or cosmic order.[19]

Judaism and Christianity

The number 12 is notable within the Hebrew Bible, and in Christianity:

Ishmael – the first-born son of Abraham – has 12 sons/princes (Genesis 25:16), and Jacob also has 12 sons, who are the progenitors of the Twelve Tribes of Israel.[20] 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. 12:1 mentions a womaninterpreted as the people of Israel, the Church and the Virgin Marywearing 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).

Islam

Remove ads

Timekeeping

  • The lunar year is 12 lunar months. Adding 11 or 12 days completes the solar year.[24]
  • 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.
Remove ads

In numeral systems

More information ۱۲, ១២ ...

In science

In sports

Remove ads

In technology

Music

Music theory

Art theory

  • There are twelve basic hues in the color wheel: three primary colors (red, yellow, blue), three secondary colors (orange, green, purple) and six tertiary colors (names for these vary, but are intermediates between the primaries and secondaries).
Remove ads

In other fields

Thumb
12 stars are featured on the Flag of Europe.
  • There are 12 troy ounces in a troy pound (used for precious metals).
  • Twelve of something is called a dozen.
  • In the former British currency system, there were twelve pence in a shilling.[25]
  • In English, twelve is the number of greatest magnitude that has just one syllable.
    Thumb
    The numerical range on the analog clock ends at 12.
  • 12 is the last number featured on the analogue clock, and also the starting point of the transition from A.M. to P.M. hours or vice versa.
  • There are twelve months within a year, with the last one being December.
  • 12 inches in a foot.
  • 12 is slang for Police officers because of the 10-12 Police radio code.

Notes

  1. Specially, a passage referring to Judas Iscariot as "one of the twelve" (an of ðæm tuelfum).[6]

References

Sources

Further reading

Loading related searches...

Wikiwand - on

Seamless Wikipedia browsing. On steroids.

Remove ads