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The PHP sqrt() function is used to return the square root of the given number. It returns NAN for the square root of a negative number.

Syntax

sqrt(number)

Parameters

number Required. Specify a number.

Return Value

Returns the square root of the specified number (returns NAN for negative number).

Example:

In the below example, sqrt() function is used to find out the square root of the given number.

<?php
  echo "The square root of 25 is: ".sqrt(25)."\n";
  echo "The square root of 30 is: ".sqrt(30)."\n";  
  echo "The square root of 35.5 is: ".sqrt(35.5)."\n";
  echo "The square root of -25 is: ".sqrt(-25)."\n";
?>

The output of the above code will be:

The square root of 25 is: 5
The square root of 30 is: 5.4772255750517
The square root of 35.5 is: 5.9581876439065
The square root of -25 is: NAN

❮ PHP Math Functions