Unknown Square iPhone/iPod Touch

Unknown Square 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.

The Challenge

Users begin to explore algebraic thinking by developing strategies to solve for unknowns found in a 3x3 array of values. Horizontal, vertical, and diagonal sums for the values are shown.