Flip the calculator so that the back case is facing you.

Use a Phillips #0 screwdriver to remove the single screw from the battery cover at the top of the back case.

Keep the screw in a safe place to use when replacing the battery cover later.

If the screw does not unfasten easily, do not force it to avoid stripping the screw. If the screw is already stripped refer to the How to Remove a Stripped Screw guide.