numbers in words - 6

in_words_-6.rb

class Integer
  def in_words
    if self < 20
      {1 => "one", 
       2 => "two",
       3 => "three",
       4 => "four",
       5 => "five",
       6 => "six",
       7 => "seven",
       8 => "eight",
       9 => "nine",
       10 => "ten",
       11 => "eleven",
       12 => "twelve",
       13 => "thirteen",
       14 => "fourteen",
       15 => "fifteen",
       16 => "sixteen",
       17 => "seventeen",
       18 => "eighteen",
       19 => "nineteen"}[self]
    end
  end
end