WHen I was using the calculator, the computing button was on the screen for a long time (all I was asking hp to do was to do a simple division). SO, I went on to take the battery out and put it back. Then, the screen turns to a full black scrren with the computing sign on there. I do not know now to fix it. The calculator just do not turn on or off or cancel!! Pls help me out, apprecipated.
Carmela