One of the problems I have with attempting the mental abbacus method is that I find it difficult to distinquish between 3 and 4 beads. So I imagined it would be a good idea to experiment with a simplified version of the abbacus. I don’t know if what I have come up with is original, so if any abbacus expert on this forum knows if it is, please let me know.

- Just like with a normal abbacus, the right column is for the single digit numbers and the second column from the right is for tens;
- You can only use 2 beads and/or an orange (or choose favorite color) card representing repectively 1 and 5 each;
- 1/2 = 1/2 bead(s) at the bottom of square a; 3/4 is 2/1 beads at the cealing of square a (so 3 = 5 - 2 and 4 = 5 - 1); 5 is a card; 6/7 = 1/2 bead(s) at the bottom of square b; 8/9 is 2/1 beads at the ceiling of square b (8 = 10 - 2, etcetera).

I have not completely found out all the strategies you need to use for doing calculations, but I plan on working on that in the future.

Annyway, I would appreciate any kind of input on this system.