Which of the following is not an operating system?

In windows calculator we use '+'  button to____________.

_______________ is placed at the extreme left corner of the task bar.

______________ is used to move up to the last visited folder.

The start button is located in ____________.

When we switch on the computer the first thing that we see on the monitor is ______

_______________ looks and operating like an ordinary calculator.

Which of the following is not an accessory of windows?

_________ button is used to reduce the size of the window.

______________ button is used to close a window.