unit Unit1;

interface

uses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, StdCtrls, Buttons, Menus;

type
  TForm1 = class(TForm)
    Label1: TLabel;
    Edit1: TEdit;
    Label2: TLabel;
    Edit2: TEdit;
    Button1: TButton;
    Label3: TLabel;
    CheckBox1: TCheckBox;
    BitBtn1: TBitBtn;
    MainMenu1: TMainMenu;
    Menu1: TMenuItem;
    N1: TMenuItem;
    N2: TMenuItem;
    procedure Button1Click(Sender: TObject);
    procedure BitBtn1Click(Sender: TObject);
    procedure N1Click(Sender: TObject);
    procedure N2Click(Sender: TObject);
    procedure CheckBox1Click(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;

var
  Form1: TForm1;

implementation

{$R *.dfm}

procedure TForm1.Button1Click(Sender: TObject);
var i,k:extended;a,b:string;
begin
  if Edit1.Text <> ''
  then
    begin
      a:=Edit1.Text;b:=Edit2.Text;
      i:=StrToFloat(a);k:=StrToFloat(b);
      Form1.Label3.Caption:=FloatToStr(i*k);
    end
  else Label3.Caption:='!!!ОШИБКА!!!';
end;

procedure TForm1.BitBtn1Click(Sender: TObject);
begin
Close;
end;

procedure TForm1.N1Click(Sender: TObject);
var i,k:extended;a,b:string;
begin
  if Edit1.Text <> ''
  then
    begin
      a:=Edit1.Text;b:=Edit2.Text;
      i:=StrToFloat(a);k:=StrToFloat(b);
      Form1.Label3.Caption:=FloatToStr(i*k)
    end
  else Label3.Caption:='!!!ОШИБКА!!!';
end;

procedure TForm1.N2Click(Sender: TObject);
begin
Close;
end;

procedure TForm1.CheckBox1Click(Sender: TObject);
var i,k:extended; a,b:string;
begin
CheckBox1.Checked:= true;
 if Edit1.Text <> ''
 then
   begin
       a:=Edit1.Text;b:=Edit2.Text;
       i:=StrToFloat(a);k:=StrToFloat(b);
       Form1.Label3.Caption:=FloatToStrF(i*k,ffFixed,3,2);
   end
   else Label3.Caption:='!!!ОШИБКА!!!';
CheckBox1.State:=cbUnChecked;
       Button1Click(Sender);
end;

end.