The goal of this app is to learn abacus and calculate these questions by mental arithmetic within 5 seconds. All lessons of the abacus lesson series, which have been highly evaluated all over the world, are recorded. The lessons have been reworked in a more polite and easy-to-understand. In addition, we have added unique training methods such as training focusing on finger movements and mental arithmetic training to improve mental arithmetic in order to learn abacus more efficiently. And various improvements have been made. - Either vertical screen or horizontal screen can be selected. - The position and size of the abacus and window can be freely laid out. - No ads. - Added sound variations. Volume control can also be finely set. - The color of the abacus can be set freely. - Earn a trophy by achieving the goal. - Smoother operability by optimizing the app. ◆Support web page 　https://hirokuma.blog/?p=4427 ◆Twitter 　https://twitter.com/p4pLIabLM00qnqn ◆Instagram 　https://www.instagram.com/hirokuma.app/