ฟังก์ชั่น number_format

<?
  $number = 123456789.2501;
  echo number_format( $number )."<br />"; //123,456,789
  echo number_format( $number , 2 )."<br />"; //123,456,789.25
  echo number_format( $number , 2 , '%' , '#' )."<br />"; //123#456#789%25
?>