It’s a function which is a lot simpler than you think. Though there might be a .NET function already in existence for this, the following function (written in PHP) does the job. It shouldn’t be too hard to port it over.
function ordinal($num) {
$ones = $num % 10;
$tens = floor($num / 10) % 10;
if ($tens == 1) {
$suff = "th";
} else {
switch ($ones) {
case 1 : $suff = "st"; break;
case 2 : $suff = "nd"; break;
case 3 : $suff = "rd"; break;
default : $suff = "th";
}
}
return $num . $suff;
}