function DecToRoman(Decimal: LongInt): string;
const
  Romans: array[1..13] of string =
  ('I', 'IV', 'V', 'IX', 'X', 'XL', 'L', 'XC', 'C', 'CD', 'D', 'CM', 'M');

  Arabics: array[1..13] of Integer =
  (1, 4, 5, 9, 10, 40, 50, 90, 100, 400, 500, 900, 1000);
var
  i: Integer;
  scratch: string;
begin
  scratch := '';
  for i := 13 downto 1 do
    while (Decimal >= Arabics[i]) do
    begin
      Decimal := Decimal - Arabics[i];
      scratch := scratch + Romans[i];
    end;
  Result := scratch;
end;