Adding zero to any number doesn’t change the value. For this reason, we call 0 the additive identity. The opposite of a number is its additive inverse. The reciprocal of a number is its multiplicative...Adding zero to any number doesn’t change the value. For this reason, we call 0 the additive identity. The opposite of a number is its additive inverse. The reciprocal of a number is its multiplicative inverse. A number and its reciprocal multiply to 1, which is the multiplicative identity. The product of any real number and 0 is 0. Zero divided by any real number except zero is zero. But division by zero is undefined.