sub ordinate ($) {
    my $num = shift;
    $num =~ s/(\d*(11|12|13|4|5|6|7|8|9|0))$/$1th/
    or $num =~ s/(\d*(1))$/$1st/
    or $num =~ s/(\d*(2))$/$1nd/
    or $num =~ s/(\d*(3))$/$1rd/;
    
    return $num;
}