This is application of brain training.
You calculate two numbers next to each other and answer the ones digit.

You can train your brain by calculating earnestly.

This application has two modes.

1. Number of questions : Compete for the time that you calculate the number of questions.
2. Time limit : Compete for the number of questions that you can calculate in time limit.
*In each mode,you can select addition or subtraction or multiplication.
(When a value is minus,you answer the absolute value.)