2- (mid game) if you do (2-1=1) and (1=1) you get the same score and money, i think it would be great if getting answers differently would have different score (maybe a multiplier for each slot used) this issue doesn't show up late game since large numbers typically have 1 solution
3- (late game) large numbers typically have 1 solutions and you most likely don't know it (: i found myself more and more trying to get 'close' to the answer instead of finding the actual answer (maybe that's intended?), I'd love a way to get more tries for each question, would encourage trying to get the exact answer by trying out different numbers (maybe just being able to see the result without submitting it as the answer)
that's my main review of the game (apologies if it's long XD)