Calculate! - Mental Math

With this app, you can practice mental math as you like.

You are free to adjust the number of digits to be included in mental arithmetic from at least one digit to a maximum of nine digits, and the number of problems to be solved at a time.
Incorrect problems can be solved again after a test.
You can also save and check your test history and improve your mental math ability.

Key Features:
-Multiple selection of four arithmetic operations
-Directly set the number of digits (1 to 9 digits) and the number of problems (1 to 9999) for mental calculation
-Display achievement and accuracy of your mental math
-Solve the wrong problem again
-Test history analysis