The product of two real numbers is 1, so these two numbers are reciprocal. For example, the following sets of numbers are reciprocal:

The numerator and denominator are also interchangeable: the reciprocal of 5/3 is 3/5.

3 and 1/3 5/3 and 3/5 -0.5 and -2.

In addition, the reciprocal of 1 and-1 is itself, because zero cannot be divisible, so zero has no reciprocal.

In addition, there is a saying that two numbers whose product is negative 1 are negative reciprocal.

Formally, the reciprocal of a fraction is exactly the reciprocal of its numerator denominator.

Essentially, the product of two reciprocal numbers is 1.