randomNumber.php

<?php
function generateRandomNumber($length)
{
    list($usec, $sec) = explode(' ', microtime());
    srand((float) $sec + ((float) $usec * 100000));
    $validchars = "0123456789";
    $number = "";
    $counter = 0;
    while ($counter < $length) {
        $actChar = substr($validchars, rand(0, strlen($validchars)-1), 1);
        $number .= $actChar;
        $counter++;
    }
    return (int) $number;
}