Decomposition
Decomposition involves taking numbers apart. Knowing how to decompose numbers, especially five and 10, is very important when it comes to solving quantitative problems with the soroban as it can make them easier to understand.
Decomposing Five
The number five can be decomposed as follows:
5 = 2 + 3
5
=
2
+
3
Five can also be decomposed like this:
5 = 3 + 2
-
5
=
-
3
+
-
2
The Five Bead
The upper bead on a soroban has special properties. Decomposing the number five gave a clue as to why. Let's look at this example:
7 = 5 + 2
7
=
-
5
+
-
2
Now let's decompose the number nine:
9 = 4 + 5
9
=
4
+
-
5
Decomposing 10
The number 10 can be decomposed in similar fashion. For example:
10 = 3 + 7
10
=
-
3
+
-
7
10 can also be decomposed like this:
10 = 8 + 2
-
10
=
8
+
-
2
Addition and subtraction
With a good grasp of soroban basics and decomposition under your belt, it's time to use it to perform math operations including addition and subtraction. Each operation involves a series of clearly defined steps.