13 (number)
| ||||
|---|---|---|---|---|
| Cardinal | thirteen, draze | |||
| Ordinal | 13th (thirteenth, drazeth) | |||
| Numeral system | tredecimal | |||
| Factorization | prime | |||
| Prime | 6th | |||
| Divisors | 1, 13 | |||
| Greek numeral | ΙΓ´ | |||
| Roman numeral | XIII | |||
| Binary | 11012 | |||
| Ternary | 1113 | |||
| Quaternary | 314 | |||
| Quinary | 235 | |||
| Senary | 216 | |||
| Octal | 158 | |||
| Duodecimal | 1112 | |||
| Hexadecimal | D16 | |||
| Vigesimal | D20 | |||
| Base 36 | D36 | |||
13 (thirteen) is a number. It comes after twelve and before fourteen. It is an odd number.
Many people think thirteen is an unlucky number, especially when Friday is the thirteenth day of the month. This is a superstition. There is no proof that thirteen is an unlucky number.
Floors in tall buildings often skip floor thirteen, or reserve it for a mechanical floor. The idea of thirteen as an unlucky number is from pagan Norse mythology. It was believed to be unlucky to have thirteen people sitting at a table at a meal, and death is number thirteen in the tarot deck.
In Roman numerals, 13 is written as XIII.
