In mathematics, a multiplicative inverse for a number x, enoted by 1⁄x or x −1, is a number which when multiplied by x yields the multiplicative identity, 1. The multiplicative inverse of x is also called the reciprocal of x. The multiplicative inverse of a fraction p⁄q is q⁄p. For the multiplicative inverse of a real number, divide 1 by the number. For example, the reciprocal of 5 is one fifth (1⁄5 or 0.2), and the reciprocal of 0.25 is 1 divided by 0.25, or 4. The reciprocal function, the function ƒ(x) that maps x to 1⁄x, is one of the simplest examples of a function which is self-inverse.