## How to calculate factorial in php | Factorial program in php | factorial recursion

The factorial of a number is the product of all integers up to and including that number, so the factorial of 5 is 120.

Example

``````4! = 4*3*2*1 = 24
5! = 5*4*3*2*1 = 120 ``````

## Points to be noted.

• It is denoted by n! and is calculated only for positive integers.
• Factorial of 0 is always 1
• The simplest way to find the factorial of a number is by using a loop or Using recursive method

## factorial program in php using for loop

``````<?php
\$num = 5;
\$fact = 1;
for(\$i = 1; \$i <=\$num;\$i++) // initially, i = 1
{
\$fact = \$fact * \$i; //
}
echo "factorial of \$num is = ".\$fact;
?>``````

Note : Above code will be iterate : 1 * 2* 3* 4* 5 = 120

## Factorial in PHP

``````<?php
\$num = 7;
\$fact = 1;
for(\$i = \$num; \$i >= 1; \$i--) // intiallly, i = 7
{
\$fact = \$fact * \$i; //
}
echo "factorial of \$num is = ".\$fact;
?>``````

Note : Above code will be iterate : 7*6*5 * 4* 3* 2* 1 = 5040

## factorial program in php using recursion | factorial recursion

``````<?php
function getFactorialofNumber(\$number){
if(\$number <= 1){
return 1;
}
else{
return \$number * getFactorialofNumber(\$number - 1);
}
}

echo "factorial of 6 is = ".getFactorialofNumber(6);
?>``````