Mental arithmetic training application.
If you win 10 games in a row, you will go to the next level.
level1 : 14-1, 17-1, ...
level2 : 13-2, 16-2, ...
level3 : 15-4, 18-6, ...
level4 : 43-3, 87-7, ...
level5 : 25-2, 29-5, ...
level6 : 36-4, 38-6, ...
level7 : 45-3, 87-4, ...
level8 : 30-10, 90-10, ...
level9 : 50-20, 80-20, ...
level10 : 70-50, 100-40, ...
In Japan, 7-8 years old (2nd grade)