OK, so I have officially destroyed a calculator attempting to take it apart but all is not lost. I have found out how to actually do this now. There are 4 screws (two under the rubber foot pads at the top) on the back of the calculator. This is not the end of the screws though. There are two screws under the screen cover that is glued/taped into place. You will need to remove this clear plastic screen cover first in order to access them. Making things further difficult these are a security screw I have never encountered before. It is almost hourglass shaped. They are located in the spots shown in the attached image. It is likely easier to remove this if heated. I cracked it by prying to hard and quickly.
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