My 2x2 shows the multiplication table of a number. Preset values are 1 to 20, but you can also manually enter any number up to 999,999. Use of simple multiplications tables for a kid learning math is quite obvious.
My son (and app co-author) used to manually build a similar table for divisions with divisors having multiple digits, and got the idea form it. A kid using this app cannot directly do complex operations, like with a calculator, but has to follow the proper math process, and can do it even if he has a hard time learning the multiplication tables.