Introducing Abacus Challenge, an iOS application.

Using a Soroban 4+1 style abacus, Abacus Challenge randomly generates numbers to add or subtract and will signal when you have the correct answer. Back and forwards buttons allow you to see if you have made a mistake. Works in portrait or landscape. Work at your own pace, or against the clock. 日本語対応。 支持中文。

Want to see Abacus Challenge in action? Watch the video below...