twelve

Twelve is the natural number following eleven and preceding thirteen. It is denoted by the symbol 12. In arithmetic, twelve is even and composite, with divisors 1, 2, 3, 4, 6, and 12, and its prime factorization is 2^2 × 3. The Roman numeral for twelve is XII, and in binary it is 1100.

Twelve plays a central role in timekeeping and measurement. There are twelve months in the Gregorian calendar and twelve signs of the zodiac. A clock is commonly divided into twelve hours, and a circle can be divided into 12 equal sectors. The term dozen denotes a quantity of twelve, and a gross equals twelve dozen (144). Some mathematical and numeration systems use base-12 (duodecimal) representations, which take advantage of 12’s multiple factors.

Cultural and symbolic usage of twelve is widespread. In Christianity, Jesus’ apostles are traditionally described as the Twelve. In Judaism, there are twelve tribes of Israel. Classical mythology often features a group of twelve Olympian gods. In science, magnesium has atomic number 12.