| base 18 | octal (base 8) | base 18 | octal (base 8) |
|---|---|---|---|
| 1 | = 1 | b | = 13 |
| 2 | = 2 | c | = 14 |
| 3 | = 3 | d | = 15 |
| 4 | = 4 | e | = 16 |
| 5 | = 5 | f | = 17 |
| 6 | = 6 | g | = 20 |
| 7 | = 7 | h | = 21 |
| 8 | = 10 | 10 | = 22 |
| 9 | = 11 | 11 | = 23 |
| a | = 12 | 12 | = 24 |
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) | base 18 | octal (base 8) | base 18 |
|---|---|---|---|
| 1 | ≈ 1 | 13 | ≈ b |
| 2 | ≈ 2 | 14 | ≈ c |
| 3 | ≈ 3 | 15 | ≈ d |
| 4 | ≈ 4 | 16 | ≈ e |
| 5 | ≈ 5 | 17 | ≈ f |
| 6 | ≈ 6 | 20 | ≈ g |
| 7 | ≈ 7 | 21 | ≈ h |
| 10 | ≈ 8 | 22 | ≈ 10 |
| 11 | ≈ 9 | 23 | ≈ 11 |
| 12 | ≈ a | 24 | ≈ 12 |
| base 18 | octal (base 8) |
|---|---|
| 1 | = 1 |
| 2 | = 2 |
| 3 | = 3 |
| 4 | = 4 |
| 5 | = 5 |
| 6 | = 6 |
| 7 | = 7 |
| 8 | = 10 |
| 9 | = 11 |
| a | = 12 |