Octal
The base-8 number system that uses eight unique symbols (0, 1, 2, 3, 4, 5, 6, and 7), where each digit represents three binary digits, starting from the right.
For example, the binary representation for decimal 74 is 0b1001010, which groups into 001 001 010 — so the octal representation is 112.
Whereas in decimal systems, each decimal place is a base of 10
74 = 7 x 10^1 + 4 x 10^0
in octal numerals, each place is a power with base 8:
112 = 1 x 8^2 + 1 x 8^1 + 2 x 8^0
By performing the octal calculation, you can see 112 (octal) = 64 + 8 + 2 = 74 (in decimal).
Though octal is sometimes used in computing, instead of hexadecimal, hexadecimal is generally the more straightforward format and is used throughout the documentation.
Source: Wikipedia
