module InWords
  def in_words()
    written_num =
      ["zero", "one", "two", "three", "four", "five", "six", "seven", "eight", "nine", "ten", "eleven", "twelve", "thirteen", "fourteen", "fifteen", "sixteen", "seventeen", "eighteen", "nineteen", "twenty"]
    written_special_num = { 3 => "thir", 4 => "for", 5 => "fif", 11 => "eleven", 12 => "twelve", 20 => "twenty" }
    num_in_words = ""
    num = self.to_s.split(//)

    if self < 1000

      if (self < 20)
        return written_num[self]
      end

      if (self >= 100) && (self < 1000)
        num_in_words = written_num[num[0].to_i] + " hundred "
      end

      if (self < 100)
        num = [0, num[0], num[1]]
      end

      case num[1].to_i
      when 1
        return num_in_words + written_num[[num[1], num[2]].join.to_i].to_s
      when 2
        num_in_words += written_num[20].to_s #+ " " + written_num[num[2]]
      when 3..5
        num_in_words += written_special_num[num[1].to_i].to_s + "ty "# + written_num[num[2]]
      when 6..9
        num_in_words += written_num[num[1].to_i].to_s + "ty " #+ written_num[num[2]]
      else
        #num_in_words += written_num[num[2].to_i].to_s
      end

      return num_in_words + written_num[num[2].to_i].to_s

    else
      puts "Your number is not less than 1000"
      return num_in_words
    end
  end
end

class Fixnum
  include InWords
end