I like this game. It really keeps you on your toes. I notice I do best when I'm well-rested and have eaten and haven't been staring at the screen for a while, especially after a nap. But that's all tests, I guess. It helps to practice some of those basic operations. For instance I noticed it kept asking me to multiply by 14 & 15, so I memorized my 14's and 15's (up to 20), and it really shaved lots of seconds off my time. Ditto practicing adding and subtracting single digits by memory. The only thing I wish is that it were more interactive. It says I'm ranked at No. 105 in the world challenge, but it doesn't say how many people are playing. If I'm 105 out of 500, that's no big deal. But 105 out of 100,000- that would be something! Also, I wish there were a way to challenge friends or see your friends or classmates ranked. Maybe challenge friends "Friends with Words" style. Or introduce a multiplayer challenge/race mode where you can drop bombs on people to slow them down or something. As it is now, it's like I'm the only person in the world playing it, and that makes for a less pleasant experience in the long run. Perhaps that makes people delete the app after a while.