An alternative representation of numbers in a fixed-radix number system. In a complement system each positive integer is represented in its usual form in the given radix system except that it is prefixed by at least one leading zero. Each negative number is then represented by the complement of the corresponding number. For example, in both the ten's complement system and the nine's complement system any number with leading digit 9 represents a negative number. See also radix complement, radix-minus-one complement.