Returning the original number and an ordinal suffix.

Ordinal numbers

* @author Venkat K
* @see http://www.eggheadcafe.com/community/aspnet/3/43489/hi.aspx
* @param {Number} A positive number.
* @returns the original number and an ordinal suffix.
* @type String
Number.prototype.toOrdinal = function() {
    var n = this % 100;
    var suffix = ['th', 'st', 'nd', 'rd', 'th'];
    var ord = n < 21 ? (n < 4 ? suffix[n] : suffix[0]) : (n % 10 > 4 ? suffix[0] : suffix[n % 10]);
    return this + ord;
}