In the last example we start by adding 6 to the abacus. Next add 4 to 6 using the 10 pair addition rule. So first add 1 to the next rod left, rod A, and then subtract 6, the 10 pair complement of 4, from 6 on rod B. The interim sum is now 10. Next subtract 1 from 10 by subtracting 1 from 0 on rod B. Again we will need to use the 10 pair subtraction rule. First subtract 1 from 1 on the next rod left, rod A, and add 9, the 10 pair complement of 1, to 0 on rod B. The interim sum is now 9. Lastly add 8 to 9 on rod B by using the 10 pair addition rule. First add 1 to 0 on next rod left, rod A, and subtract 2, the 10 pair complement of 8, from 9 on rod B. The final answer is 17.