[NumLock]

Код:

type
  TDBGrid = class(DBGrids.TDBGrid)
  public
    property VisibleColCount;
    property VisibleRowCount;
  end;

  TForm1 = class(TForm)
    DBGrid1: TDBGrid;
    DataSource1: TDataSource;
    Table1: TTable;
    Timer1: TTimer;
    procedure Timer1Timer(Sender: TObject);

procedure TForm1.Timer1Timer(Sender: TObject);
begin
  Caption:=IntToStr(DBGrid1.VisibleRowCount);
end;