<?php 
// extract numbers from a string 

$string = "The 1. Quick and 2. Brown fox said 3. (!@*(#!@*"; 

$new_string = ereg_replace("[^0-9]", "", $string); 


echo $new_string; 
// output: 123
?>

Will help convert string to number  OR get number in a selected string.

Extract Numbers from a string

php, number

PHP