The 15 (number) reference article from the English Wikipedia on 24-Apr-2004 (provided by Fixed Reference: snapshots of Wikipedia from wikipedia.org)

15 (number)

15 (fifteen) is the natural number following 14 and preceding 16.

List of numbers — Integers
0 10 11 12 13 14 15 16 17 18 19 20 30
Cardinal	fifteen
Ordinal	fifteenth
Factorization
Roman numeral	XV
Binary	1111
Hexadecimal	F

In mathematics

Fifteen is a triangular number and a hexagonal number, and the 4th Bell number. Fifteen is the double factorial of 5. It is a composite number; its proper divisors being 1, 3 and 5.

In hexadecimal, as well as all higher bases, fifteen is represented as F.

Fifteen is the magic constant of a 3 by 3 magic square:

In other fields

• The Lo Shu Square, used in Feng Shui, is a 3x3 magic square with magic constant 15.

Age 15 is:

• The age of a quinceañera, a Hispanic girl celebrating her fifteenth birthday.
• The age for obtaining a driver's (or learner's) permit in jurisdictions where the age for a driver's license is sixteen.

Fifteen is:

• The atomic number of phosphorous
• The number of days in each of the 24 cycles of the Chinese solar year.
• The number of guns in a gun salute to Army, Air Force and Marine Corps Lieutenant Generals, and Navy and Coast Guard Vice Admirals.
• The designation of Interstate 15, a freeway that runs from California to Montana.
• The number of players on a rugby union team.
• The number of checkers each side has in the beginning of a backgammon game.
• Fifteen, a television program.
• The number of balls in the eight ball variant of billiards
• Historical years: 15 A.D., 15 B.C, or 1915

This is the "15 (number)" reference article from the English Wikipedia. All text is available under the terms of the GNU Free Documentation License. See also our Disclaimer.