convert to Japanese Numerals

number_converter.rb

class BigDecimal
  SUFFIX = [['京', 16], ['兆', 12], ['億', 8], ['万', 4]]

  def convertNumber2JapaneseNumerals
    number ||= self
    number_string ||= ''

    SUFFIX.each do |suffix|
      if number.exponent >= suffix[1]
        number_string += number.div(10 ** suffix[1]).to_s + suffix[0]
        number = number.remainder(10 ** suffix[1])
      end
    end

    return number_string + number.split[1].to_s
  end
end