from
The Free On-line Dictionary of Computing (8 July 2008)
octal
<mathematics> Base 8. A number representation using the
digits 0-7 only, with the right-most digit counting ones, the
next counting multiples of 8, then 8^2 = 64, etc. For
example, octal 177 is digital 127:
digit weight value
1 8^2 = 64 1* 64 = 64
7 8^1 = 8 7* 8 = 56
7 8^0 = 1 7* 1 = 7
---
127
Octal system used to be widespread back when many computers
used 6-bit {bytes}, as a 6-bit byte can be conveniently
written as a two-digit octal number. Since nowadays a byte is
almost always 8-bit long the octal system lost most of its
appeal to the {hexadecimal} system.
For a brief discussion on the word `octal' see {hexadecimal}.
(1997-06-16)