<?php
    function nth( $rank ) {
        if ( $rank > 20 )
          $rank %= 10;

        if ( $rank  == 1 )
            return "st";
        elseif ( $rank == 2 )
            return "nd";
        elseif ( $rank == 3 )
            return "rd";
        else
            return "th";
    }
?>