Check out Jungle Coins and Jungle Time - great for concept review (2.99 each)
Link to App:http://itunes.apple.com/us/app/jungle-coins-learn-coin-math/id380864501?mt=8
Numbl - Single or multiplayer activity - (99 cents)
Some reviewers said:
Who knew addition could be so addictive? Numbl is an entertaining math workout for your brain. It's perfect for a quick game, or an endless two-player battle against a friend!
Numbl tests your simple, speedy addition skills. To play, touch numbered tiles as fast as you can to reach a target sum, which is displayed at the top of the screen. Once each tile is used, it disappears. See how quickly you can clear the screen. You'll be surprised at how soon your skills improve!
Link to app: http://itunes.apple.com/us/app/numbl-number-jumble-fun-for/id364902680?mt=8
Audio Slide A Math: (free)
Additions Lite - offers and intuitive and innovative way for preschool children to lean basic number additions. Each question comes with pictures and voice so kids can learn to count, add and speak at the same time.
Link to App: http://itunes.apple.com/us/app/audio-slide-a-math-additions/id423958229?mt=8