15 (fifteen) is the natural number following 14 and preceding 16. In English, it is the smallest natural number with seven letters in its spelled name.
Fifteen is the magic constant of the unique order-3 normal magic square:
In science
- The atomic number of phosphorus.
- Group 15 of the periodic table are sometimes known as the “Pnictogens“.
In Pakistan
15 Madadgar is designated as an emergency number in Pakistan, for mobile phones, similar to the international GSM emergency number 112, if 112 is used in Pakistan, then the call is routed to 15. 112 can be used in an emergency even if the phone is locked and does not have a SIM card in it.
In Judaism
- In the Hebrew numbering system, the number 15 is not written according to the usual method, with the letters that represent “10” and “5” (י-ה, yodh and heh), because those spell out one of the Jewish names of God. Instead, the date is written with the letters representing “9” and “6” (ט-ו, teth and vav)
Age 15
- The age of a quinceañera, a Hispanic girl celebrating her 15th birthday. Thus, Spanish bingo callers might refer to the number 15 as la niña bonita (the beautiful girl).
- The age for obtaining a driver’s (or learner’s) permit in certain jurisdictions, including some, where the legal age for a driver’s license is 16.
- In the UK a minor can be sent to prison to await trial at the age of 15.
- In some countries it is the legal age for sexual intercourse.
- In the UK it is the legal age to watch a BBFC “15” rated film in a cinema or purchase a “15” rated film or video game.
In other fields
Fifteen total individuals in the molluskspecies Donax variabilis comprise the entire coloration and patterning in their phenotypes.
Fifteen is:
- The number of days in each of the 24 cycles of the Chinese calendar.
- The number of guns in a gun salute to Army, Marine Corps, and Air Force Lieutenant Generals, and Navy and Coast Guard Vice Admirals.
- The number of checkers each side has at the start of a backgammon game.
- The number of balls in the eight ball variant of billiards
- The number of letters in the words “uncopyrightable”, “dermatoglyphics“, “misconjugatedly”, and “hydropneumatics”, which are thelongest words in the English language that do not repeat a letter.
- The number of minutes in one quarter of an hour; 15 minutes past or before an hour is often known as quarter past and quarter to, respectively.