Arne roman numerals part 2

gistfile1.txt

class RomanNumerals

  def initialize
    @reference = {"1"=> "I", "5"=> "V", "10" => "X", "50"=> "L", "100" => "C", "500"=> "D", "1000"=> "M",
                  "4"=> "IV", "9"=>"IX","40" => "XL", "90" => "XC", "400"=> "CD", "900" => "CM"}
  end

  def to_roman(number,long_string = '')
    @reference.keys.map{|i| i.to_i}.sort.reverse.each do |i|
      count,number = difference(number,i.to_i)
      long_string = create_string(count,long_string,@reference[i.to_s])
    end
    return long_string
  end

  def create_string(times,string,character)
    return string if times == 0
    create_string(times -=1, string<<character, character)
  end

  def difference(number,denom,count = 0)
    return [count,number] if (number - denom) < 0
    difference((number - denom),denom,count+=1)
  end

end