I didn't really like the first one. If you want to upgrade it, do you know what you should do? NOT MAKE IT 10 EVERY TIME! Some other modularities. OR how about you use different number bases altogether. Like a little note at the bottom of each level that says what base it's in and what the magic number to aim for is - maybe you'll have one level where it's in hexadecimal and the goal number is "C" (12 in decimal). But THIS? But when you have multiplication symbols do you know what I have to do that I didn't before? I have to actually count all the numbers on the screen together at the beginning of the level, so that I say "oh, ok, this one is 7 mod 10 so I need to start by moving that 1 into the x4 box so that it adds 3 mod 10" or "this one is 4 mod 10 so the thing I need to negate is that +2", adding up all the numbers together at the beginning is really, really annoying. It is NOT the way to knock this game up a notch.
Level 7 dividing. What the hell. It starts 0 mod 10. There's no way to divide by 4 or divide by 5 alone without the possibility of doing it to 0. Which means you must do it to 2
Essentially, this isn't a good addition to the previous game. That was a good start but this is a step in a bad direction.