I don't think obfuscation is the purpose of the effect in the math lab. The purpose of showing this in the lab is to show kids how they can use the commutative property in action to do something pretty amazing to those who behold it. The illusion definitely hinges on the correct calculation of four multiplications (top¹ x top², bottom¹ x bottom², top¹x bottom², and top² x bottom¹) and three additions (tt+bb, tb+tb, and then those two sums added together) and this would certainly obfuscate the method from a magician's audience. For this reason I would not normally do this trick as an opening or closing effect - and I definitely wouldn't do this in an environment where my spectators' ability to do math is impaired (for example, at a bar) or even just not likely to be that great. This trick needs to happen in the middle of a performance using multiple spectators and someone checking their math to make sure the effect doesn't flop because someone thought four times three was eighteen or something. I have another math trick for you