The base-12 number system composed of the digits 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, A, B. Such a system has been advocated by no less than Herbert Spencer, John Quincy Adams, and George Bernard Shaw (Gardner 1984). In fact, duodecimal still has its advocates, some of whom term it "dozenal."
Some aspects of a base-12 system are preserved in the terms dozen and gross applied to the quantities 12 and 144, respectively.
The following table gives the duodecimal equivalents of the first few decimal numbers.
| 1 | 1 | 11 | B | 21 | 19 |
| 2 | 2 | 12 | 10 | 22 | 1A |
| 3 | 3 | 13 | 11 | 23 | 1B |
| 4 | 4 | 14 | 12 | 24 | 20 |
| 5 | 5 | 15 | 13 | 25 | 21 |
| 6 | 6 | 16 | 14 | 26 | 22 |
| 7 | 7 | 17 | 15 | 27 | 23 |
| 8 | 8 | 18 | 16 | 28 | 24 |
| 9 | 9 | 19 | 17 | 29 | 25 |
| 10 | A | 20 | 18 | 30 | 26 |
