PHP | gmp_fact() for large factorials

The gmp_fact() is a built-in function in PHP which is used to calculate the factorial of a GMP number (GNU Multiple Precision : For large numbers).

Syntax:

gmp_fact ( $num )

Parameters: This function accepts a GMP number as a mandatory parameter as shown in the above syntax. It can be a GMP object in PHP version 5.6 and later, or a numeric string provided that it is possible to convert the latter to a number.This function calculates the factorial of this number and returns it.

Return Value: This function returns a GMP number which is the factorial of the number passed as parameter.

Examples:

Input : "9"
Output : 362880

Input : 25
Output : 15511210043330985984000000

Below programs illustrate the gmp_fact() function in PHP :

Program 1:

<?php
$fact = gmp_fact(5);
echo gmp_strval($fact);

?>

Output:

120

Program 2:

<?php
$fact = gmp_fact(25);
echo gmp_strval($fact);

?>

Output:

15511210043330985984000000

Reference:
http://php.net/manual/en/function.gmp-fact.php