I really enjoyed these math puzzles! Solved all of them :) If I had to give feedback, I'd suggest letting doubles stack, and also maybe incorporating some puzzles where you have to square a negative. But of course both of those suggestions require making more puzzles. I think you had a good amount of puzzles here, with nothing too complicated.
As I know from our game, making puzzles is not an easy task, as you have to manage difficulty curve and make sure everything is playtested. I think you did a good job with these here. Buuuuut if you make more... >:) I think there's a lot of potential here!