Better than the other options – Know Abacus Review

This app, as opposed to most others out there, actually teaches you how to use the soroban. Note that the explanations are very -VERY- rudimentary, yet useful. Also the explanations seem to be written by someone with little command of the English language but are decent enough to be understood with some patience. If you know zero soroban, then this app will get you to be able to do some basic math in a matter of minutes.
Review by poisa on Know Abacus.