Jacquie & Patrick tackle Numbers in Words

NumbersInWords.rb

module InWords
    def in_words
        num_digits = self.to_s.length
        num_string = self.to_s

        under_ten = { 0 => "zero", 1 => "one", 2 => "two", 3 => "three",
                        4 => "four", 5 => "five", 6 => "six",
                        7 => "seven", 8 => "eight", 9 => "nine" }
        teens = { 10 => "ten", 11 => "eleven", 12 => "twelve", 13 => "thirteen",
                        14 => "fourteen", 15 => "fifteen", 16 => "sixteen",
                        17 => "seventeen", 18 => "eighteen", 19 => "nineteen" }
        tens = { 2 => "twenty", 3 => "thirty", 4 => "forty", 5 => "fifty",
                        6 => "sixty", 7 => "seventy", 8 => "eighty", 9 => "ninety" }
        hundreds = { 1 => "one hundred", 2 => "two hundred", 3 => "three hundred", 4 => "four hundred",
                        5 => "five hundred", 6 => "six hundred", 7 => "seven hundred", 8 => "eight hundred",
                        9 => "nine hundred" }

        if num_digits == 1
          under_ten[self]

        elsif num_digits == 2
          if self >= 10 && self < 20
            teens[self]
          else
            tens[num_string[0].to_i] + " " + under_ten[num_string[1].to_i]
          end

        elsif num_digits == 3
          if num_string[1] == "1"
            hundreds[num_string[0].to_i] + " " + teens[num_string[1,2].to_i]
          elsif num_string[1] == "0"
            hundreds[num_string[0].to_i] + " " + under_ten[num_string[2].to_i]
          else
            hundreds[num_string[0].to_i] + " " + tens[num_string[1].to_i] + " " + under_ten[num_string[2].to_i]
          end
        end
    end
end

class Fixnum
    include InWords
end