Calculate! - Mental Math

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