Factorial Program
Factorial Program
The factorial of a number n is defined by the product of all the digits from 1 to n (including 1 and n).
For example,
4! = 4*3*2*1 = 24
6! = 6*5*4*3*2*1 = 720 
<?php
$num = 4;
$factorial = 1;
for ($x=$num; $x>=1; $x--)
{
$factorial = $factorial * $x;
}
echo "Factorial of $num is $factorial";
?> 
<html>
<head>
<title>Factorial Program using loop in PHP</title>
</head>
<body>
<form method="post">
Enter the Number:<br>
<input type="number" name="number" id="number">
<input type="submit" name="submit" value="Submit" />
</form>
<?php
if($_POST){
$fact = 1;
//getting value from input text box 'number'
$number = $_POST['number'];
echo "Factorial of $number:<br><br>";
//start loop
for ($i = 1; $i <= $number; $i++){
$fact = $fact * $i;
}
echo $fact . "<br>";
}
?>
</body>
</html> 
<?php
function fact ($n)
{
if($n <= 1)
{
return 1;
}
else
{
return $n * fact($n - 1);
}
}
echo "Factorial of 6 is " .fact(6);
?> 