Square number

A square number, sometimes also called a perfect square, is the result of an integer multiplied by itself. 1, 4, 9, 16 and 25 are the first five square numbers. In a formula, the square of a number n is denoted ${\displaystyle n^{2}}$ (exponentiation), usually pronounced as "n squared". The name square number comes from the name of the shape; see below.

Square numbers are non-negative. Another way of saying that a (non-negative) number is a square number, is that its square root is again an integer. For example, ${\displaystyle {\sqrt {9}}=3}$, so 9 is a square number.