put commas in the number

[devWhiz]

<?php
echo "How much money do you want landed on the account?!\n";
$landed = fgets(STDIN);
$calc = ($landed * .25);
$total = ($landed + $calc);
echo "\nYou need to list the dummy for $".$total."...\n\n";
echo "Press enter to close this script...";
$exit = fgets(STDIN);
?>

 

so say I enter

 

12000000000 which would make the $total .. $15000000000

 

how so I make the total have commas in it, like $15,000,000,000

[litebearer]

http://www.w3schools.com/PHP/func_string_money_format.asp