Octal number system

The octal (or octonary) number system is a number system with a base of 8. An octal digit is exactly three binary digits as 8=2^3, which is why it's main use is binary compression. This can be seen below:

Base theory
Due to being a power of 2 base, only dyadic fractions terminate in octal, although fractions involving thirds and ninths have fairly short reptends.