Fungi Perkalian Pada Delphi

var
  Form1: TForm1;

a,b,c:real;

implementation

{$R *.dfm}

procedure TForm1.Edit2Change(Sender: TObject);

begin
a:=StrToIntDef(DBEdit1.Text,0);
b:=StrToIntDef(Edit2.Text,0);
c:=a*b;
Edit3.Text:=FloatToStr(c);
if Edit2.Text='' then
ShowMessage('data harus di isi');
Form1.Refresh;