Octal (Base-8)

Of course 10 and 2 are not the only possible bases to use for a number system. In fact, any integer (or even non-integer) base can be used. There are two more bases, however, that are commonly used when working with computers.

The octal system uses 8 as its base. Thus we have

2365₁₀ = 4475₈

because

2365₁₀ = 4 * 8³ + 4 * 8² + 7 * 8¹ + 5 * 8⁰

We only need eight "digits" for octal numbers: 0,1,2,3,4,5,6,7.