12 (number)

The number twelve, or 12, comes right after eleven and before thirteen. It is a special number in mathematics because it can be divided evenly by many smaller numbers, making it very useful.

Twelve is important in how we measure time. Many clocks are made with twelve hours, and our calendar system often uses groups of twelve months.

This number also appears in many important religions and cultures around the world, making it a number with deep meaning for people.

Name

Twelve is the largest number with a single-syllable name in English. Early Germanic numbers might not have been based on ten. This is shown in unusual ways people said eleven and twelve, and in old words for groups of 120. These special ways of speaking slowly disappeared when people started using Arabic numbers during the 12th-century Renaissance.

The words for twelve come from Old English. They have similar sounds in all Germanic languages, like the German word zwölf. The usual way to say the position of twelve is "twelfth," but sometimes "dozenth" or "duodecimal" is used, especially when talking about base-12 numbers. A group of twelve things is usually called a "dozen," but it can also be called a "dodecad" or "duodecad." The adjective for twelve is "duodecuple."

In mathematics

12 is a special number in math. It is the smallest abundant number, which means it has more factors than one might expect. It is also a highly composite number and has many divisors.

In shapes, a twelve-sided polygon is called a dodecagon. A regular dodecahedron has twelve pentagonal faces. Regular cubes and octahedrons both have 12 edges, and regular icosahedrons have 12 vertices.

The number twelve appears in many mathematical ideas and patterns, making it quite important in the subject.

Religion

The number twelve is important in many religions and stories. It often means something complete or perfect.

In Judaism and Christianity, twelve appears many times. For example, Jacob had twelve sons, who became the Twelve Tribes of Israel. In Christianity, Jesus had twelve followers called the twelve Apostles. The Book of Revelation also uses the number twelve in many ways.

In Islam, the number twelve is mentioned several times in the Koran. For example, there are twelve springs and twelve leaders mentioned. In Shia Islam, there are twelve important leaders called the Twelve Imams.

In astrology, there are also twelve signs in both Western astrology and Hindu astrology.

Timekeeping

The number twelve is important in how we measure time. Many calendars have twelve months in a year, and there are twelve hours on a clock for both morning and afternoon. For example, 12:00 p.m. is noon, and 12:00 a.m. is midnight.

The basic units of time, like seconds and minutes, can also be divided evenly by twelve. This makes twelve a useful number in timekeeping.

In numeral systems

In science

Force 12 on the Beaufort wind force scale is the strongest wind speed, which happens during a hurricane.

In sports

In soccer and American football, the number 12 often stands for the fans because they support the 11 players on the field. For example, Texas A&M University keeps the number 12 jersey for a special player who represents a fan known as the "12th Man." Some teams like Bayern Munich, Hammarby, Feyenoord, Atlético Mineiro, Flamengo, Seattle Seahawks, Portsmouth, and Cork City do not let players wear the number 12 on their jerseys because it is saved for their fans.

In rugby league, one of the starting forwards usually wears the number 12 jersey. In rugby union, one of the centre players often wears the number 12 shirt.

In technology

ASCII and Unicode use a special code point for something called "form feed".

Music

Music theory

Twelve is important in music. It is the number of different pitches in an octave and the number of major keys and minor keys in common tuning used today. The twelfth is the interval of an octave and a fifth, and some instruments like the clarinet follow this pattern.

The twelve-tone technique is a special way of writing music created by Arnold Schoenberg. Another common pattern in popular music is the twelve-bar blues.

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.

In other fields

There are 12 troy ounces in a troy pound, which is used for precious metals. Twelve of something is called a dozen. In the old British money system, there were twelve pence in a shilling.

Twelve is the last number on an analogue clock and marks the change from A.M. to P.M. There are twelve months in a year, with the last one being December. Also, there are 12 inches in a foot.