I used to love “Egyptian Ratscrew” (also called “Egyptian Rat Slap” for the more easily offended I suppose). We used to play it all the time in my Physics/Calculus class. It combined the speed of “Speed” with the ferocity of “Spoons” without all the injuries.
True, I’m guessing “Equation Ratscrew” won’t engender quite the excitement of the original, but nevertheless, here it is. Might make for some decent equation practice.