Casio FX-991CW Battery Replacement

First, take the protective cover off the calculator.

Then, turn the calculator over.

Remove the Philips screw that holds the battery cover in place in the top-right corner.

Then lift the cover off by lifting the right side of the cover up, and slide it out.

Take a pointy, flat tool, like a flathead screwdriver, to pry the battery out of the compartment.

Insert the new battery into the calculator by sliding it into place, then pushing it down, to ensure a good connection.

Slide the battery cover into place.

Then install the screw.

Tighten the screw.

NOTE: BELOW THIS GUIDE, THERE IS A NOTE THAT SAYS "TO REASSEMBLE THIS DEVICE, FOLLOW THESE DIRECTIONS IN REVERSE ORDER." DO NOT FOLLOW THAT STEP, AS THIS GUIDE IS COMPLETE!