unit Unit1;

interface

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

type
  TForm1 = class(TForm)
    Edit1: TEdit;
    Edit2: TEdit;
    Edit3: TEdit;
    Button1: TButton;
    Label1: TLabel;
    Label2: TLabel;
    Label3: TLabel;
    Button2: TButton;
    Button3: TButton;
    Button4: TButton;
    Button5: TButton;
    Button6: TButton;
    procedure Button1Click(Sender: TObject);
    procedure Button3Click(Sender: TObject);
    procedure Button2Click(Sender: TObject);
    procedure Button4Click(Sender: TObject);
    procedure Button5Click(Sender: TObject);
    procedure Button6Click(Sender: TObject);
  private
    { Private declarations }
    a, b, c: real;
  public
    { Public declarations }
  end;

var
  Form1: TForm1;

implementation

{§R *.DFM}

procedure TForm1.Button1Click(Sender: TObject);
begin
    a := StrToFloat(Edit1.text);
    b := StrToFloat(Edit2.text);
    c := a + b;
    Edit3.Text := FloatToStr(c);
end;

procedure TForm1.Button2Click(Sender: TObject);
begin
    a := StrToFloat(Edit1.text);
    b := StrToFloat(Edit2.text);
    c := a - b;
    Edit3.Text := FloatToStr(c);
end;

procedure TForm1.Button3Click(Sender: TObject);
begin
    a := StrToFloat(Edit1.text);
    b := StrToFloat(Edit2.text);
    c := a * b;
    Edit3.Text := FloatToStr(c);
end;

procedure TForm1.Button4Click(Sender: TObject);
begin
    a := StrToFloat(Edit1.text);
    b := StrToFloat(Edit2.text);
    c := a / b;
    Edit3.Text := FloatToStr(c);
end;

procedure TForm1.Button5Click(Sender: TObject);
begin
    Edit1.Text := '0';
    Edit2.Text := '0';
    Edit3.Text := '';
end;

procedure TForm1.Button6Click(Sender: TObject);
begin
    Form1.Close;
end;

end.