Adding with Five Extras and Ten Extras

Short Course

This is a short course (slide show) in the basic concepts to subtract using the Ten (10) Extras principle.

Putting it all together

Up to this point, you have studied the five (5) extras principle for addition and subtraction and the ten (10) extras principle for addition. To add any two integers or groups of integers, you will need to use all of these principles. Sometimes you may need to use a combination both the five (5) extras principle and the ten (10) extras principle and several columns to complete the calculation and sometimes you will not. To add two integers with the Cranmer abacus, you may need to:

Add a digit directly
Add a digit using the five (5) extras principle
Add a digit using the ten (10) extras principle and the five (5) extras principle for addition or subtraction
Add a digit using the ten (10) extras principle and the five (5) extras principle for addition or subtraction involving several columns

This is a table of all steps you have learned for adding the digits 1 through 9. You may choose to remember the detailed steps or just refer to five (5) extras principle for addition and subtraction and/or the ten (10) extras principle.

0114 Table of Five and Ten Extras .pdf

Examples

Now, let’s look at several examples that will show you how to combine the principles you have learned. As we have done in all of the previous examples:

Set all the digits of the first number
Working left to right, add each digit of the second number. Continue adding until you completed adding the digit in the unit column.
If there are more integers, repeat step 2 for each integer until you reach the final sum.