octal number system

Number system to the base eight, used in computing. The highest digit that can appear in the octal system is seven. Whereas normal decimal, or base-ten, numbers may be considered to be written under column headings based on the number ten, octal, or base-eight, numbers can be thought of as written under column headings based on the number eight. The octal number 567 is therefore equivalent to the decimal number 375, since (5 × 64) + (6 × 8) + (7 × 1) = 375.

The octal number system is sometimes used by computer programmers as an alternative to the hexadecimal number system.