In this video I have explained the situations when we need to use the Combination Formulas for Subtraction on the Abacus and how to think about it and use it. Remember that Combination Formulas are to be used only in certain situations while adding or subtracting digits greater than 5.
For details on Abacus Practice Worksheet Sets for Addition, Subtraction, Multiplication & Division, visit the following Blog page:
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Негізгі бет Abacus || English || Lesson 7: When & How to use Combination Formulas (Subtraction)
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