| base 21 | senary (base 6) | base 21 | senary (base 6) |
|---|---|---|---|
| 1 | = 1 | b | = 15 |
| 2 | = 2 | c | = 20 |
| 3 | = 3 | d | = 21 |
| 4 | = 4 | e | = 22 |
| 5 | = 5 | f | = 23 |
| 6 | = 10 | g | = 24 |
| 7 | = 11 | h | = 25 |
| 8 | = 12 | i | = 30 |
| 9 | = 13 | j | = 31 |
| a | = 14 | k | = 32 |
The senary numeral system (also known as base-6 or heximal) has six as its base. It has been adopted independently by a small number of cultures. Like decimal, it is a semiprime, though being the product of the only two consecutive numbers that are both prime (2 and 3) it has a high degree of mathematical properties for its size. As six is a superior highly composite number, many of the arguments made in favor of the duodecimal system also apply to this base-6.
| senary (base 6) | base 21 | senary (base 6) | base 21 |
|---|---|---|---|
| 1 | ≈ 1 | 15 | ≈ b |
| 2 | ≈ 2 | 20 | ≈ c |
| 3 | ≈ 3 | 21 | ≈ d |
| 4 | ≈ 4 | 22 | ≈ e |
| 5 | ≈ 5 | 23 | ≈ f |
| 10 | ≈ 6 | 24 | ≈ g |
| 11 | ≈ 7 | 25 | ≈ h |
| 12 | ≈ 8 | 30 | ≈ i |
| 13 | ≈ 9 | 31 | ≈ j |
| 14 | ≈ a | 32 | ≈ k |
| base 21 | senary (base 6) |
|---|---|
| 1 | = 1 |
| 2 | = 2 |
| 3 | = 3 |
| 4 | = 4 |
| 5 | = 5 |
| 6 | = 10 |
| 7 | = 11 |
| 8 | = 12 |
| 9 | = 13 |
| a | = 14 |