Abacus Lesson -ADD and SUB- is an educational app designed to teach users addition and subtraction using an abacus. The abacus, known as "Soroban" in Japan, is a simple calculator used in various countries including China, Japan, and Korea. Despite the availability of modern calculators on smartphones, the abacus remains a valuable tool for mental calculation.

One of the key advantages of the abacus is its simplicity. Unlike electronic calculators, the abacus can be used mentally without the need for physical tools. This app aims to develop users' mental calculation skills by providing practice in performing calculations up to three digits.

With Abacus Lesson -ADD and SUB-, users can learn and practice addition and subtraction using the abacus, enhancing their calculation abilities in their daily lives. The app offers a user-friendly interface and clear instructions, making it accessible to users of all ages.

Whether you are a student looking to improve your math skills or an adult seeking to sharpen your mental calculation abilities, Abacus Lesson -ADD and SUB- is a valuable educational tool that can help you enhance your calculation skills.