The octal numeral system, or oct for short, is the base-8 number system, and uses the digits 0 to 7. Octal numerals can be made from binary numerals by grouping consecutive binary digits into groups of three (starting from the right). For example, the binary representation for decimal 74 is 1001010. Two zeroes can be added at the left: (00)1 001 010, corresponding the octal digits 1 1 2, yielding the octal representation 112.
| octal (base 8) | senary (base 6) | octal (base 8) | senary (base 6) |
|---|---|---|---|
| 1 | = 1 | 13 | = 15 |
| 2 | = 2 | 14 | = 20 |
| 3 | = 3 | 15 | = 21 |
| 4 | = 4 | 16 | = 22 |
| 5 | = 5 | 17 | = 23 |
| 6 | = 10 | 20 | = 24 |
| 7 | = 11 | 21 | = 25 |
| 10 | = 12 | 22 | = 30 |
| 11 | = 13 | 23 | = 31 |
| 12 | = 14 | 24 | = 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) | octal (base 8) | senary (base 6) | octal (base 8) |
|---|---|---|---|
| 1 | ≈ 1 | 15 | ≈ 13 |
| 2 | ≈ 2 | 20 | ≈ 14 |
| 3 | ≈ 3 | 21 | ≈ 15 |
| 4 | ≈ 4 | 22 | ≈ 16 |
| 5 | ≈ 5 | 23 | ≈ 17 |
| 10 | ≈ 6 | 24 | ≈ 20 |
| 11 | ≈ 7 | 25 | ≈ 21 |
| 12 | ≈ 10 | 30 | ≈ 22 |
| 13 | ≈ 11 | 31 | ≈ 23 |
| 14 | ≈ 12 | 32 | ≈ 24 |
| octal (base 8) | senary (base 6) |
|---|---|
| 1 | = 1 |
| 2 | = 2 |
| 3 | = 3 |
| 4 | = 4 |
| 5 | = 5 |
| 6 | = 10 |
| 7 | = 11 |
| 10 | = 12 |
| 11 | = 13 |
| 12 | = 14 |