PHP Math functions =D

math.php

<?php

/**
 * Computes the factorial of $n
 * @param interger $n Number you want to find the factorial for
 * @return string
 */
$factorial = function($n) {
    for($k=1, $i=1;$i <= $n;$i++) {
      $k = $k * $i; 
    }   

    // convert
    $k = sprintf('%f',$k);

    // return the number only
    return substr($k, strpos($k, '.'), 0); 
};

/**
 * Returns the number of combinations
 * @param integer $x Total numbers
 * @param integer $y Total choosen
 * @return string
 */
$combin = function($x,$y) use($factorial)
{
    return $factorial($x)/($factorial($y)*$factorial($x-$y));
};