Interesting concept! It’s very fun to discover and parsing out the rules just by playing. There’s also some nice emergences with some timers getting “out of sync” (impossible to align properly with odd and even numbers) but the x2 being able to fix that (since it can change an odd to an even). I’m also proud to have beaten the last level the “hard” way (went for the smaller ones first, then multiplied them until I obtained 386 that with a x2 landed exactly on 772 ^^).
Although I wonder how some levels could better enforce some solutions. Levels being open and allowing several solutions is a strength, but it makes brute-forcing the default solution for most levels. There might be ways to design puzzles that restrict the players a bit more in order to teach them advanced strategies.
In any case, it’s a neat puzzle to complete. Well done!