procedure TForm1.Button1Click(Sender: TObject);
begin
ShowMessage(Format('%8.2f',
[(StrToFloatDef(Edit1.Text,0)+StrToFloatDef(Edit2.Text,0)+
StrToFloatDef(Edit3.Text,0)+StrToFloatDef(Edit4.Text,0)+
StrToFloatDef(Edit5.Text,0)+StrToFloatDef(Edit6.Text,0))/6]));
end;