Abacus Math Program – Lesson 3 – Simple Addition and Subtraction

In abacus math lesson 3 we are ready to look at combining numbers by adding and subtracting numbers within a single rod on the abacus or soroban. If you are not sure about how to enter or remove any of the digits 1 through 9 on the abacus, please take a look at abacus math lesson 1 for counting 0 to 5 and abacus math lesson 2 for counting 6 through 9. None of these examples will require the use of complements, i.e. the need to borrow from or carry to the next adjacent rod, and therefore will be straightforward. All operations can be worked out on a single rod. However, pay close attention to the actual bead movements and associated fingering to ensure consistent practice to gain speed and accuracy.

Consider the following simple addition and subtraction problems with their associated bead mechanics. The number at the tip of an arrow represents the value of the bead(s) to be moved. The circled numbers represent the order of the bead movements.

In the first trivial problem lets add 1 to abacus by moving 1 lower bead with the thumb to the reckoning bar. Next add 2 to the abacus by moving 2 more lower beads with the thumb to the reckoning bar. This gives us the final sum of 3 on the abacus.

In this next example we first add 2 to the abacus by moving 2 lower beads with the thumb to the reckoning bar. Then add 5 to 2 by pulling down the upper 5 bead with the index finger to the reckoning bar for a final sum of 7 on the abacus.

In this next example we will use our pinch finger movement. Add 1 to the abacus by moving 1 lower bead with the thumb to the reckoning bar. Next add 7 to 1 on the abacus by pinching both the upper 5 bead and 2 lower beads to the reckoning bar. The abacus shows us the final sum is 8.

Now let’s look at first simple subtraction problem. Add 9 to the abacus by pinching all the beads to the reckoning bar. Subtract 5 from 9 on the abacus by moving the upper 5 bead with the index finger away from the reckoning bar for a final sum of 4.

Next let’s look at a subtraction problem with a reverse pinch. First add 8 to the abacus by pinching both the upper 5 bead and 3 lower beads to the reckoning bar. Next we will subtract 6 from 8 by first removing the 5 bead with the index finger away from the reckoning bar and then again with the index finger move 1 lower bead away from the reckoning bar. Remember beads are counted on the abacus when they either touch the reckoning bar directly or indirectly through another bead. In subtracting the 6 we could have done it in one finger movement by reverse pinching with both the index and thumb together. It is a preference which technique is used.

These simple examples show how quickly very young students can learn to represent and recognize all our base 10 digits 0 through 9 and do simple addition and subtraction operations. Building on these fundamental abacus math concepts and techniques, students will be able to quickly move on to more advanced and challenging math problems. Next up Lesson 4 Multidigit Addition and Subtraction.