Adds ordinalize i.e. th,st,rd to a number for use in date string outputs

fixnum_ordinalize.rb

class Fixnum
  def ordinal
    abs_number = self.abs
    if (11..13).include?(abs_number % 100)
        "th"
    else
      case abs_number % 10
      when 1; "st"
      when 2; "nd"
      when 3; "rd"
      else    "th"
      end
    end
  end
  def ordinalize
      "#{self}#{ordinal()}"
  end
end

Adapted from this rails code