I never fully understood the current scientific RPN calculator, but I would find it more handy if the Pre had a TI calculator (with/without graphing) for calculus. I need to be able to use derivatives and integrals. I couldn't find out how to do that with the RPN. Basically would require a whole new app for my tastes anyways.
If I helped you or you have downloaded one of my files,
then least you could do is click the "Thanks" button.