Mental arithmetic training application.
If you win 10 games in a row, you will go to the next level.
level1 : 67-50, 94-40, ...
level2 : 69-32, 77-61, ...
level3 : 20-4, 20-7, ...
level4 : 40-9, 70-6, ...
level5 : 81-5, 31-3, ...
level6 : 62-8, 74-9, ...
level7 : 35-8, 51-4, ...
level8 : 62-17, 71-12, ...
level9 : 85-27, 48-29, ...
level10 : 65-47, 92-36, ...
In Japan, 7-8 years old (2nd grade)