The multiplicative inverse of a number is the number that, when multiplied by the original number, gives a product of 1. For example, the multiplicative inverse of 2 is 1/2, since 2 * 1/2 = 1.
Zero does not have a multiplicative inverse because there is no number that, when multiplied by zero, gives a product of 1. For example, 0 * any number = 0.