Roman_numbers.rb

# Convert Decimals to Roman numerals...
#
module Roman
  ROMAN_STEPS =
  {
    'M' => 1000, 'CM' => 900,
    'D' => 500,  'CD' => 400,
    'C' => 100,  'XC' => 90,
    'L' => 50,   'XL' => 40,
    'X' => 10,   'IX' => 9,
    'V' => 5,    'IV' => 4,
    'I' => 1
  }

  def to_roman
    deci  = self
    roman = ''

    ROMAN_STEPS.each do |k, v|
      while deci > v - 1
        roman += k
        deci -= v
      end
      break if deci == 0
    end
    roman
  end
end

# Extend Numeric Class
class Numeric
  include Roman
end