Numbers to Words (up to 999) in ruby

InWords

module InWords

def in_words

ones = {
    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 => "fifthteen",
    16 => "sixteen",
    17 => "seventeen",
    18 => "eighteen",
    19 => "nineteen" }

tens = {
    0 => "",

    2 => "twenty",
    3 => "thirty",
    4 => "fourty",
    5 => "fifty",
    6 => "sixty",
    7 => "seventy",
    8 => "eighty",
    9 => "ninety" }

number_in_words = ""

first_digit = ""
second_digit = ""
third_digit = ""
second_and_third_digits = ""



case self.to_s.length
  when 1
    puts "Num is single digit"
    number_in_words = ones[self]

  when 2
    puts "Num is double digits"
    if number_in_words = teens[self]
        puts "Num is in the Teens"
    else
       puts "Num is not in the Teens"
       first_digit = self/10
       number_in_words = tens[first_digit]

       if (self % 10) == 0
            puts "Num is a power of ten'"
       else
            puts "Num is not a power of ten'"
            second_digit = self%10
            number_in_words << ones[second_digit]
       end
    end

  when 3
    puts "Num is triple digits"
    first_digit = (self/100)
    number_in_words = ones[first_digit] + " hundred"

    if (self % 100) == 0
        puts "Num is an even hundred"

    else
        # Checks to see if we need the 'teens' hash
        second_and_third_digits = self%100
        if teens[second_and_third_digits]
            puts "Num is in the Teens"
            number_in_words << " and " + teens[second_and_third_digits]

        else
            puts "Num is not in the Teens"
            second_digit = (self %100 /10)
            number_in_words << " and " + tens[second_digit]

            if (self % 100) == 0
                puts "Num is a 'ty'"

            else
                third_digit = (self %100 %10)
                number_in_words << " " + ones[third_digit]
            end
        end

    end




  else
  "That ain't no number between 1 and 999"
end

  return number_in_words

end

end

class Fixnum
  include InWords
end