a good game, but not without flaws
At first it seems that mathematics does not make for good gameplay, but in this game, you pulled it off well. Making the game calculate automatically depending on different ways of calculation is a very good idea.
There are some flaws though. First of all, the game remains rather the same. The only real difference in each level is the height of the starting stack, which is a shame. More power ups, or a way of earning them would have been a nice additon. Also, in a game like this it would have been a good idea to give the player the choice of where to apply the powerup, seeing as the different possibilities in the stack also depended on chance; having something to break this chance (except for a higher stack) would have kept the game more interesting.
Also, there is one major exploit in the game. I wont detail it here, mostly for the enjoyment of others, but if you want to know about it, feel free to sent me a message (or, in case you already know about it, nevermind).
All in all, a good game with a very good concept, though it has more potential than what you currently put in. I hope to see a future version that is more polished, because this concept seems to be quite addicting. Keep up the good work!