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Method B - Equal Addition Method

CPD: A Compendium of Mathematical Methods (By Jo Morgan), topic 2.1.2

Equal Addition Method - Core Principle

Here we need to understand the principle that if we add or subtract the same number from both the minuend and subtrahend, then the difference doesn’t change.

Core principle

Core principle

Using a number line

Using a number line

  • It’s a good idea to demonstrate this on a number line.
  • Here, we can see that the difference between 8 and 3 is 5.
Adding 2 - number line example

Adding 2 - number line example

  • If we add 2 to both numbers, we’ve essentially translated our subtraction up the number line; the difference remains the same.

Test yourself on Method B - Equal Addition Method

  • Example question: Use the Equal Addition Method to calculate 498 − 379.

    Starting from the right, what number should a student add to both the minuend and subtrahend as the first step?

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