octal

<mathematics>

Number base eight. The octal number representation uses 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 representation used to be widespread back when many computers used six-bit bytes, as six-bits can be conveniently written as a two-digit octal number. Since nowadays a byte is almost always eight bits long, the octal system lost most of its appeal to the hexadecimal system. Octal is still found in the C programming language and its descendents where it is commonly to represent characters, as in 'A' = '\101', 101 being octal for 65, the ASCII character code for 'A'.

For a brief discussion on the word `octal' see hexadecimal.

Last updated: 2017-12-18

Nearby terms:

OC-n ♦ OCODE ♦ OCP ♦ OCR ♦ OCS ♦ octal ♦ Octave ♦ octet ♦ octothorpe ♦ OCX ♦ OD390

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