<P> In mathematics , a multiplicative inverse or reciprocal for a number x , denoted by 1 / x or x , is a number which when multiplied by x yields the multiplicative identity , 1 . The multiplicative inverse of a fraction a / b is b / a . 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 f ( x ) that maps x to 1 / x , is one of the simplest examples of a function which is its own inverse ( an involution ) . </P>
<P> In mathematics , a multiplicative inverse or reciprocal for a number x , denoted by 1 / x or x , is a number which when multiplied by x yields the multiplicative identity , 1 . The multiplicative inverse of a fraction a / b is b / a . 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 f ( x ) that maps x to 1 / x , is one of the simplest examples of a function which is its own inverse ( an involution ) . </P>
the product of a rational number and its multiplicative inverse is
the product of a rational number and its multiplicative inverse is
multiplicative identity , 1
multiplicative identity , 1