The additive identity is 0. When zero is added to any number, it does not change the value.
The opposite of a number is its additive inverse. The additive inverse of a is −a.
An irrational number is a number that cannot be written as the ratio of two integers. Its decimal form does not stop and does not repeat.
The multiplicative identity is 1. When one multiplies any number, it does not change the value.
The reciprocal of a number is its multiplicative inverse. The multiplicative inverse of a is 1a.
A rational number is a number that can be written in the form pq, where p and q are integers and q≠0. Its decimal form stops or repeats.
a real number is a number that is either rational or irrational.