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# Twelve

Twelve (12) is the natural number following eleven and preceding thirteen.

Twelve is a composite number, its proper divisors being 1, 2, 3, 4 and 6. Twelve is also a highly composite number, the next one being 24.

Twelve being the product of three and four, the first four positive integers show up in the equation 12 = 3 * 4, which can be continued with the equation 56 = 7 * 8.

A twelve-sided polygon is a dodecagon. A twelve-sided polyhedron is a dodecahedron.

The number twelve is often used as a sales unit in trade, and is often referred to as a dozen. Twelve dozen are known as a gross. (Note that there are thirteen loaves in a baker's dozen.) The duodecimal system (twelve = 10), which is the use of 12 as a division factor for many historical weights and measures, including hours, probably originates from Mesopotamia. See also: base 12. As Schoolhouse Rock explains in its song "Little Twelvetoes", if man had been born with twelve fingers, he would have counted and multiplied using the duodecimal system.

In English, twelve is the number of greatest magnitude that has just one syllable.

In base thirteen and higher bases (such as hexadecimal), twelve is represented as C.

There are twelve months in a year.

The Western zodiac has twelve signs, as does the Chinese zodiac.

There are twenty-four hours in a day in all, with twelve hours for a half a day. The hours are numbered from one to twelve for both the ante meridiem (a.m.) half of the day and the post meridiem (p.m.) half of the day. 12:00 after a.m. and before p.m. (in the middle of the day) is noon, and 12:00 after p.m. and before a.m. (in the middle of the night) is midnight. A new day is considered to start with the stroke of midnight.

The minute hand of a clock face turns twelve times faster than the hour hand.

There are normally twelve pairs of ribs in the human body.

Jewish tradition and the old testament of the Bible talks of twelve tribes of Israel. The new testament of the Bible describes twelve apostles of Jesus Christ.

In modern Jewish practice, girls get their bat mitzvah on the Shabbat after their twelfth birthdays.

In the United States, twelve people are appointed to sit on a jury for felony trials in all but four states, and in federal and D.C courts. The number of jurors in the movie gave the title to the film 12 Angry Men.

Other movies with the number twelve in their titles include 12 Monkeys and Twelve Chairs

The song Twelve Days of Christmas came from the traditional practice of extending Yuletide celebrations over twelve days.

Twelfth Night, another name for the 12th Day of Christmas or January 6, gives its name to a Shakespeare comedy, as well as that of progressive rock band; see Twelfth Night (band).

Twelve is also

• The atomic number of magnesium.
• ASCII and Unicode code point for form feed.
• In music, the number of pitch classes in an octave, not counting the duplicated pitch. Also, the total number of major keys, (not counting enharmonic equivalents) and the total number of minor keys (also not counting equivalents).
• The designation of United States Interstate 12, a freeway in Louisiana.