Adding with Five Extras

Short Course

This is a short course (slide show) in the basic concepts to add using the Five (5) Extras principle.

The Five (5) Extra Principle for Addition

In the Direct Addition page, we added each digit of the number by pushing the exact number bead to the bar. However, what do we do if we want to add the integers 1, 2, 3, 4 or 5 this may not be possible. One approach we can use is to add 5 (which is too much unless you want to add 5) and remove the extra.

· We want to add 1. Instead, we add 5 and remove the extra, 4. (5 – 1).

· We want to add 2. Instead, we add 5 and remove the extra, 3. (5 – 2)

· We want to add 3. Instead, we add 5 and remove the extra, 2. (5 – 3)

· We want to add 4. Instead, we add 5 and remove the extra, 1. (5 – 4)

· We want to add 5. Nothing extra (5 – 5)

This is five (5) extras principle for addition: Add 5 and remove the extra.

Important: To apply the five (5) extras principle for addition, the most efficient way to move the 5 bead to the bar first and then remove the extra beads from below the bar in one continuous motion. This is very efficient technique that will become important as you develop more calculating speed.

Adding using the Five (5) Extra Principle

When we need to add the integers 1, 2, 3, 4, or 5, but the beads we need below the bar aren’t available, but the 5 bead is available, then we can use the five (5) extras principle. In this principle we will push the 5 bead to the bar (set 5) and then clear (remove) the extra beads from the bar to get the number that you originally wanted to add.

Examples

Let’s look at some examples of how this principle is applied:

• Example: 4 + 1

• Example: 4 + 2

• Example: 4 + 3

• Example: 4 + 4

• Example: 4 + 5

• Example: 423 + 144

• Example: 430 + 235

• Example: 2,313 + 3,143

• Example: 2,534 + 242

• Example: 14,231 + 42,334

Build Your Skill

Now you are ready to try some calculations on your own. Click on this link for some problems and their solutions to test your skill.