HowTo: PHP – Raise a Number to the Power of Another (exponent in PHP)

You might need to raise a number to the power of another in a PHP script, for example $3^5 = 3 \times 3 \times 3 \times 3 \times 3$ (sometimes written 3^5), or in general $x^n$ . This may also be used with negative powers where $x^{-n} = \frac{1}{x^n}$ . Of course, you’d probably want to do this for more complicated examples!

PHP has a function built in to do this: $x^n =$ pow(x,n).

Examples of ‘Power Of’

Here are some examples, which raise a number to the power of another and display the output. In the examples, <br /> inserts a line break to display the results neatly.

<?php
echo "3^5 = " . pow(3,5) . "<br />"; // 243
echo "2^9 = " . pow(2,9) . "<br />"; // 512
// Anything raised to the power of 0 is 1:
echo "99^0 = " . pow(99,0) . "<br />"; // 1
// Negative powers:
echo "3^-1 = 1/3 = " . pow(3,-1) . "<br />"; // 1/3 = 0.3333
echo "3^-2 = 1/(3^2) = " . pow(3,-2) . "<br />"; // 1/9 = 0.1111
echo "<br />";

// Loop through 2 raised to the 0,1,2,...,10:
for($i=0;$i<=10;$i++)
{
  echo "2^" . $i . " = " . pow(2,$i) . "<br />";
}
?>

Output of the example:

3^5 = 243
2^9 = 512
99^0 = 1
3^-1 = 1/3 = 0.33333333333333
3^-2 = 1/(3^2) = 0.11111111111111

2^0 = 1
2^1 = 2
2^2 = 4
2^3 = 8
2^4 = 16
2^5 = 32
2^6 = 64
2^7 = 128
2^8 = 256
2^9 = 512
2^10 = 1024

Good luck! If you have any questions about this article then please post a comment!