Connect Sums iPhone/iPod Touch 
Connect Sums is a "Math Doodles" challenge that provides plenty of addition and subtraction practice, within a recreational math setting. The mathematical puzzle allows users to play with different representations of numbers, while developing their number sense to create strategies to help them solve problems.
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The Challenge
Users develop their number sense by trying to clear series of random values presented in a 4x4 array. Selected values are cleared when their sum equals the target sum. Users can choose from 25 different value representations and two levels of difficulty.