function DecToRoman(Decimal: Cardinal): string;
const
  Numbers: array [1 .. 13] of Integer = (1, 4, 5, 9, 10, 40, 50, 90, 100, 400,
    500, 900, 1000);
  Romans: array [1 .. 13] of string = ('I', 'IV', 'V', 'IX', 'X', 'XL', 'L',
    'XC', 'C', 'CD', 'D', 'CM', 'M');
var
  i: Integer;
begin
  Result := '';
  for i := 13 downto 1 do
    while (Decimal >= Numbers[i]) do
    begin
      Decimal := Decimal - Numbers[i];
      Result := Result + Romans[i];
    end;
end;

procedure TForm1.Button1Click(Sender: TObject);
begin
  ShowMessage(DecToRoman(8));
  ShowMessage(DecToRoman(736));
end;