Numeric Value: 15

The folowing table expresses '15' in various number bases. 'DRx' shows the result of 'digit reducing' resulting in an X-digit long number.

BaseDR4DR3DR2DR1
21111100 1
3 120101
4  33,123
5  303
6  235
7  213
8  17,101
9  167
10  156
11  145
12  134
13  123
14  112
15  101
16   F

Math World

Factors: 3 * 5

15 is in the Pythagorean Triples: (8, 15, 17), (15, 112, 113).

15 is the sum of the counting numbers from 1 to 5 (See 'The Sum/Product of the First N Counting Numbers').

A 'Pentadecagon' is a 'regular polygon' with 15 sides.

Physical World

15 is the atomic weight of Phosphorus (P).