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). Some aspects of a base-12 system are preserved in the terms dozen and gross. 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 |
Base, Decimal, Dozen, Gross, Hexadecimal
Gardner, M. The Sixth Book of Mathematical Games from Scientific American. Chicago, IL: University of Chicago Press, pp. 104-105, 1984.