Numbers in computers are usually of two types: integers and floating point (reals.) As in mathematics, integers may be negative or positive or 0. Oftentimes only positive integers are needed and these are called unsigned integers.

Integers are encoded using base 2 or binary. This is a positional representation system that is identical in concept to base 10 or base 8 or base 5. Each "digit" of a numeral (this is what we call a written representation of a number) is assigned to a place, or power of the base. Here is a binary number written out to show its powers of 2.