type
  IMoney = interface
    function Value: Currency;
  end;

  TPercentCalculated = class(TInterfacedObject, IMoney)
  public
    constructor Create(
      OriginalValue, Percent: Currency);
    class function New(
      OriginalValue, Percent: Currency): IMoney;
    function Value: Currency;
  end;

implementation

constructor TPercentCalculated.Create(
  OriginalValue, Percent: Currency);
begin
  FOriginalValue := OriginalValue;
  FPercent := Percent;
end;

class function TPercentCalculated.New(
  OriginalValue, Percent: Currency): IMoney;
begin
  Result := Create(OriginalValue, Percent);
end;

function TPercentCalculated.Value: Currency;
begin
  if FPercent > 0 then
    Result := (FOriginalValue * Percent) / 100
  else
    Result := FOriginalValue;
end;

end.