Thirteen

Thirteen (13) is the natural number following twelve and preceding fourteen.

Thirteen is the 6th smallest prime number, the next is seventeen.

13 goes into 999,999 exactly 76,923 times, so fractions with 13 in the denominator have six digit repeating sequences in their decimal expansions.

In base fourteen and higher bases (such as hexadecimal), thirteen is represented as D.

Thirteen is also:

• Regarded as an unlucky number in many cultures. Unreasoned fear of the number 13 is termed triskaidekaphobia. Due to this fear, some tall buildings have resorted to skipping the thirteenth floor or having a 12a-th floor instead. The thirteenth of a month is likewise ominous, at least when it falls on a Friday.
• Regarded as a lucky number in China because it is synonymous with 實生 which means "must be alive". However 13 is regarded as unlucky by those Chinese under the influence of foreign cultures.

In the Christian religion, the number is considered significant since there were thirteen present at the Last Supper. Also, if both Judas and Matthias are counted, there were thirteen apostles. Thirteen was also once associated with the Epiphany by Christians, the Christ child having received the Magi on his thirteenth day of life.

There are thirteen loaves in a baker's dozen.

In bingo it is called Unlucky for some.

Thirteen is the age of majority in Jewish tradition. Boys get their bar mitzvah on the Shabbat after their thirteenth birthdays.

Strauss and Howe named Generation X the "Thirteenth Generation".

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See also: eleven, twelve, thirteen, fourteen, fifteen integer, list of numbers.

This article is about the number. For the year AD 13, see 13.