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How to Add and Subtract with an Abacus

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Soroban
Before reading this lesson, you should already know how to read a Japanese abacus. If you have no idea about it, don’t fret. You can read my lesson on reading a Japanese abacus.

Adding and subtracting with an abacus is simple and easy to learn. It just takes some practice to feel confident enough to replace it with your calculator. To make things simpler, I will teach you addition first. Anyway, all of us have learned to make an addition before subtraction!

Lesson 1

With a Single Rod

Make sure your abacus is in zero value (all heavenly beads up and all earth beads down). Choose a unit rod. I always choose the one near the center.

Problem #1: 1+1=?
In the unit rod you’ve chosen, raise a single earth bead. Now you have a value of 1. Just leave the bead there and raise another earth bead. Now you have two earth beads. So, the answer is 2!

Note: It is important for you to say the problem out loud while moving the beads. For example, as you’re raising the first bead, say “one”, then before proceeding, say “plus”, and while raising the next bead, say the second addend, which is “1”. When the answer “appears”, say “equals [your answer]”. I know it may sound childish, but learning is quicker when you use your eyes, muscles, and mouth at the same time.

Now, let’s make it a little harder.

Problem #2: 1+2+1=?
Again, make sure your abacus is in zero value. Raise one earth bead. You will now see “1”. This time, the second addend is more than one bead. You proceed by adding another two earth beads simultaneously. You now have three raised earth beads, which is equivalent to “3”. Lastly, raise the remaining earth bead. The answer now lies in front of you – “4”.

Note that the heavenly bead remained untouched in the first two problems. What do you do if the problem involves a number “5” addend? Let’s proceed to the third problem.

Problem #3: 2+5=?
“Erase” all the digits from the previous problem. Raise two earth beads. Leave them there, and lower the lone heavenly bead directly above them. Two raised earth beads and a lowered heavenly bead is 7!

Congratulations! Now you can make simple additions with your abacus! Lesson 1 doesn’t take too much time to master. I’m sure you didn’t even sweat!

Lesson 2

With Two Rods

Math problems in the real world aren’t as simple as those in the first lesson. We often have to calculate numbers in larger amounts. In this lesson, I will teach you how to add numbers involving two rods. In layman’s terms, you will learn how to add two-digit addends with an abacus.

Problem #1: 3+10=?
In the unit rod (make sure it’s in the unit rod), raise three earth beads. Currently, you have a value of “3”. Go to the next rod on the left and raise 1 earth bead. The answer is “13”.

Problem #2: 3+10+1=?
In the unit rod, raise three earth beads. (Current answer: 3)
In the next rod to the left, raise one earth bead. (Current answer: 13)
Go back to the unit rod, raise one earth bead. (Answer: 14)

Problem#3: 20+10+5=?
In the second rod, raise two earth beads. (Current answer: 20)
In the same rod, raise one earth bead. (Current answer: 30)
In the unit rod, lower one heavenly bead. (Answer: 35)

Problem#4: 50+11+3=?
In the second rod, lower one heavenly bead. (Current answer: 50)
In the second rod, raise one earth bead; in the unit rod, raise one earth bead. (Current answer: 61)
In the unit rod, raise three earth beads. (Answer: 64)

Problem#5: 15+51=?
In the second rod, raise one earth bead; in the unit rod, lower one heavenly bead. (Current Answer: 15)
In the second rod, lower one earth bead; in the unit rod, raise one earth bead. (Answer: 66)

Lesson 3

Subtraction with one and two rods
I told you adding with a Japanese abacus is very simple. How about subtraction? Simple. Just add backwards!

Problem#1: 4-1=?
In the unit rod, raise four earth beads. (Current answer: 4)
In the unit rod, lower one earth bead. (Answer: 3)

Problem#2: 4-2-1=?
In the unit rod, raise four earth beads. (Current answer: 4)
In the unit rod, lower two earth beads. (Current answer: 2)
In the unit rod, lower one earth bead. (Answer: 1)

Problem#3: 9-5-2=?
In the unit rod, lower one heavenly bead and raise four earth beads simultaneously. (Current answer: 9)
In the unit rod, raise one heavenly bead. (Current answer: 4)
In the unit rod, lower two earth beads. (Answer: 2)

Problem#4: 34-21=?
Raise three earth beads in the second rod and raise four earth beads in the unit rod. (Current answer: 34)
In the second rod, lower two earth beads; in the unit rod, lower one earth bead. (Answer: 13)

Problem#5: 60-50=?
In the second rod, lower one heavenly bead and raise one earth bead. (Current answer: 60)
In the second rod, raise one heavenly bead. (Answer: 10)

Problem#6:55-5=?
In the second rod, lower one heavenly bead; in the unit rod, lower one heavenly bead. (Current answer: 55)
In the unit rod, raise one heavenly bead. (Answer: 50)

Problem#7: 99-45=?
In the second rod, lower one heavenly bead and raise four earth beads; do the same in the unit rod. (Current answer: 99)
In the second rod, lower four earth beads; in the unit rod, raise one heavenly bead. (Answer: 54)

Problem#8: 99-47=?
In the second rod, lower one heavenly bead and raise four earth beads; do the same in the unit rod. (Current answer: 99)
In the second rod, lower four earth beads; in the unit rod, raise one heavenly bead and lower two earth beads. (Answer: 52)

If you can do addition with two rods, I’m quite sure you will have no problem with three or more rods! But you may tell me, “Rainy, these questions are too simple. What about those involving carryovers? How do you do 9+1, 4+2, 3+3, 7+4?” Just relax. In my next lesson, I will teach you how to add with carryover. For now, practice moving the beads up and down like a pro.

© Rainy Kua 2016

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