Input the right mathematical formula!
It is easy calculation.
Both children and adults can enjoy themselves.
It is a game which inputs expression like the calculator so that it may become a numerical value displayed on the upper right.
There is the level 5 (four operations) from the level 1 (addition).
The following problem is displayed shortly after answering correctly.
It does not advance to the next in case of a mistake.
Please answer 20 questions as soon as possible.