In mathematics, a perfect square is a positive integer that is the square of some integer. For example, the numbers 1, 4, 9, 16, 25, 36, 49, 64, 81, and 100 are all perfect squares.

The square of an integer n is the product of n by itself. For example, the square of 5 is 5 × 5 = 25.

A perfect square can also be defined as an integer that has an integer square root. For example, the square root of 25 is 5.

The set of all perfect squares is infinite. This can be proven by using the fact that there are an infinite number of prime numbers. For every prime number p, the number p^2 is a perfect square.