arithmetical restorations

It is application to complete an expression using the number that 'arithmetical restorations', a given answer were appointed.
During commuting, let's strengthen brain using the time that we had free including the wait!
I do not put the unnecessary functions such as thyme limits at all to concentrate on it slowly and carefully, and to be able to think.

[How to play]
At first I choose the level with a title.
Was displayed by a screen; accept a number and a ceremony to answer.
The number can choose only a light blue button.
If a calculation formula is completed, then press the OK button.
If an expression is right, the next question is displayed.
When I want to delete an expression, then press CL button.
When you want to know the answer, please push the give up button.
When I want to try a different level, I push the button of ,up arrow button and return to a title.
When you push the operation button more than one second, a problem not to use the operation is displayed.