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In mathematics, the multiplicative inverse of a number x, denoted 1/x or x<sup> −1</sup>, is the number which, when multiplied by x, yields . The multiplicative inverse of x is also called the reciprocal of x. One computes the multiplicative inverse of a (real) number by dividing 1 by the number. For example, the reciprocal of 5 is one fifth (1/5 or 0.2), the reciprocal of 0.25 is 1 divided by 0.25, or 4. The reciprocal function, the function f(x) that maps x to 1/x, is one of the simplest examples of a function which is self-inverse.