find_roman.rb

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

def map_dat_roman(roman_mapping, number, result)
  if (number >= 1)
    k,v = roman_mapping.find { |k, v| number / k >= 1 }
    result += v
    new_number = number - k
    return map_dat_roman(roman_mapping, new_number, result)
  else
    return result
  end
end

number = 2541
result = ''

result = map_dat_roman(roman_mapping, number, result)
p result,result