I've tried all the suggestions on this board and recently used the HP12C to work through a Time Value of Money course with no problems. But today, the calculator won't perform basic arithmetical calculations such as addition, subtraction, multiplication and division.
I've removed the batteries, reset the machine and it still insists that 3 x 6 = 36, 5 + 2 = 2, 1 + 3 = 6.
This is simply bizarre. Does anyone have any suggestions? Or is it broken?
It still does TVM calculations with no problems. Go figure.
Please tell us exactly what keys you are pressing to perform each of the calculations you mentioned. We need that to determine what's causing the errors. It would also be extremely helpful if you mention what is displayed after each keystroke.