The aim of this exercise is to observe how many balls enter into a box and/or leave it. After every round you will be asked how many balls are contained in each box.
Please note, from level 12 on there will be an additional challenge to the exercise, since now the task is not just to count the number of all balls in general but only the balls of a specific color.
The clue is to stick to a special order of the boxes (e.g. clockwise) and to say aloud the amount of balls that are 'contained' in the respective boxes aloud – even if the value would be 0 – and to do so every time when a new ball is either entering or leaving a box.