Just saw this interesting and highly rated math app is free for downloading right now. Normally, it is priced at $2.99. I haven’t had a chance to test this out extensively. The game play is similar to Cut the Rope/Angry Birds.
Might be a fun way to develop math fact fluency.
Recommended for grades 3 to 5. There is a junior version of the app aimed for K-2 available as well for $2.99 on on the iPad. Wuzzit Trouble Math Junior on the App Store on iTunes.