square

The square of a number $x$ is the number obtained multiplying $x$ by itself. It’s denoted as $x^{2}$ .

Some examples:

$\displaystyle 5^{2}$	$\displaystyle=$	$\displaystyle 25$
$\displaystyle\left(\frac{1}{3}\right)^{2}$	$\displaystyle=$	$\displaystyle\frac{1}{9}$
$\displaystyle 0^{2}$	$\displaystyle=$	$\displaystyle 0$
$\displaystyle(-0.5)^{2}$	$\displaystyle=$	$\displaystyle 0.25$

A perfect square is the square of an integer. The first few perfect squares are 0, 1, 4, 9, 16, 25, $\ldots$ .