Mental arithmetic training application.
If you win 10 games in a row, you will go to the next level.
level1 : 1x3, 1x5, ...
level2 : 2x6, 2x4, ...
level3 : 3x7, 3x2, ...
...
level9 : 9x4, 9x8, ...
level10 : Review Questions
In Japan, 7-8 years old (2nd grade)