Added support for iPhone Duo. Added support for the latest iPadOS. Performed maintenance to ensure the app continues to work properly. Due to updates to our development environment, support for iOS 13 and iOS 14 has been discontinued. iOS 15 or later is now required to update or newly install the app.

Regular improvements to keep the app working properly.

Support for iOS 18.

Regular improvements to keep the app working properly.

Regular improvements to keep the app working properly.

Regular improvements to keep the app working properly.

Regular improvements to keep the app working properly.

Regular improvements to keep the app working properly.

We are making regular improvements to ensure that the app continues to work properly.

Updated sound effects. Previous sound effects can still be used.

We are making regular improvements to ensure that the app continues to work properly.

New color themes added. Different color themes can now be selected for Light Mode and Dark Mode.

We are making regular improvements to ensure that the app continues to work properly.

Let's try the mental arithmetic time trial. It measures the speed of your mental arithmetic using a more rigorous method than before. You can try from the "Challenges" button added to the home screen. Version 4.3.1: Fixed a bug related to leaderboards.

Let's try the mental arithmetic time trial. It measures the speed of your mental arithmetic using a more rigorous method than before. You can try from the "Challenges" button added to the home screen.

The result screen is now displayed when the calculation is stopped midway.

The result screen is now displayed when the calculation is stopped midway.

The result screen is now displayed when the calculation is stopped midway.

Support for iOS 15.

Fixed a bug in which the number with the larger digit was sometimes omitted in calculations where the digits of the left and right numbers were different.

Improved the readability of the graphs for daily records.

Fixed a bug that caused the time display on the result screen to be incorrect in some cases. This problem is only in the display, and the correct time is actually measured and recorded. The text size adjustment function has been adjusted to make it easier to understand.

Fixed a bug that caused the time display on the result screen to be incorrect in some cases. This problem is only in the display, and the correct time is actually measured and recorded. The text size adjustment function has been adjusted to make it easier to understand.

The text size of the entire application can now be enlarged by up to 150%. The size of the numbers on the calculation screen can now be specified from four levels.

The design has been revamped. The best time for each digit setting is now recorded. The time taken for each calculation can now be checked. The backspace key has been added. Fixed some bugs.