Squaring with PHP

How can I square using PHP? i.e. 2^2 = 4 and 4^2 = 16.

I've looked but can't find it in the manual anywhere.

Thanks......

http://uk2.php.net/sqrt

I don't want the square root. I want to square the number.

Exponentiation doesn't use ^ or ** as you might be used to with other languages. To calculate "z equals y to the x" use:

$z = pow(y,x)

http://ca.php.net/manual/en/function.pow.php

Thanks, Dylan.