Little Digits $1.99
Little Digits takes counting on fingers and transforms it into an adorable, interactive app to help kids practice counting, adding, and subtracting. Because of the multi-touch screen, the app can connect how many fingers kids are placing on the iPad's screen with what appears on the screen. parents or kids can add their own voice to the audio provided for each number, 1-10.
Coin Math- $1.99 Elementary School
This can be easily understood by Kindergartners, but yet still appeals to older students who need this practice. The advanced options gets you a longer time frame of use for this app, working for students Kindergarten through Middle School (and even longer if someone needs some practice working with money) ..
BuzzMath Middle School~ FREE
Requires iPad 2+, Internet connection. iPad 1 not supported. BuzzMath is free with an option to upgrade to premium features.