This application is the lite version of Mr. Abacus game (market://details?id=com.bbk.mrabacus), it simulates the Japanese abacus (soroban), it gives you addition (and subtraction) problems to solve in the shortest time, it can teach abacus addition (and subtraction) to kids and adults.
Future updates:-
- Add time chase mode.
- Add mental mode.
- Add slide (drag) mode to move the beads (done :) ).