Bạn có thực sự nhanh chóng để làm các tính toán? Huấn luyện tâm trí của bạn!
Locate the operation shown in transparency on the circle and get the number in the center by selecting 2 numbers from those proposed.
For each operation you have 15 seconds available to perform all the tests you want!
It's easier to do than to say!
Have fun!