Download Counting Frame
Counting Frame deals with a concept that I was never able to fully understand before trying this game, even if I am a grown up. The abacus was something really strange to me and I was never able to make some calculus using the little marbles that an abacus has but this game taught me how to do it.
You will have in front of you a simple abacus that consists of 100 marbles, the classic value, 10 of them being contained on each of the 10 different rows of the abacus. You will be able to do simple mathematics using such an instrument but it still deserves a try.