// http://en.wikipedia.org/wiki/Ordinal_number_(linguistics)

function toOrdinal(n) {
  function suffix(tens, ones) {
    if (tens != 1) {
      switch(ones) {
        case 1: return 'st';
        case 2: return 'nd';
        case 3: return 'rd';
      }
    }
    return 'th';
  }
  return n + suffix(Math.round((n % 100) / 10), n % 10);
}