I have been using Complex RPN Calculator (free) which seems to be pretty good and does RPN and complex numbers. I also use WolframAlpha but you have to be online to do computations I think. I may end up paying to get Pcalc RPN calculator. It looks quite nice.
Sounds like a bunch of BS to cover their asses. If there is one thing I have learned in Krav Maga is that men are really big and strong and that I don't want to be attacked. On the other hand, if I am every attacked, there is not going to be any backing away and calling for help!