The addition for a abacus is very simple. Make a number, add the number of beads to your abacus, then add more beads from the next number. Here is some good examples:
- 1+1=2
- 111101 110+
- 111101 110=
- 111011 110
- 4+1=5
- 101111 110+
- 111101 110=
- 111110 101
- 5+6=11
- 111110 101+
- 111101 101=
- 111110 011
Now these are for addition only so practice these. Even with rocks on your desk can work just as well as with a regular chinese abacus, although it may not be as fast.