Source: https://senecalearning.com/en-gb/revision-notes/teacher-cpd/cpd-a-compendium-of-mathematical-methods-seneca-certified/2-1-2-method-b-equal-addition-method

[Revision notes](https://senecalearning.com/en-gb/revision-notes.md) › [Teacher CPD](https://senecalearning.com/en-gb/revision-notes/teacher-cpd.md) › [CPD: A Compendium of Mathematical Methods - Seneca Certified](https://senecalearning.com/en-gb/revision-notes/teacher-cpd/cpd-a-compendium-of-mathematical-methods-seneca-certified.md) › Method B - Equal Addition Method

# 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](https://image-v2.cdn.app.senecalearning.com/2020-04/a9512a72-6ada-48be-ad44-9ffe6c7d0334/Method%20B%20-%20Theory.png)

### Using a number line

![Using a number line](https://image-v2.cdn.app.senecalearning.com/2020-04/637402b1-da84-4126-999c-b95f7c7a79d0/Untitled%20drawing%20(1).png)

- 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](https://image-v2.cdn.app.senecalearning.com/2020-04/3fd9c8f9-700c-4a71-8b07-aea183cc1b1d/Untitled%20drawing%20(2).png)

- 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?

[Practise this topic for free](https://app.senecalearning.com/classroom/course/d0e67498-99c8-47d2-ada7-cd629abed70c/section/b7264b2f-e50d-4d0f-a474-fbf62e2e7fb8/session)

- Previous topic: [2.1.1 Method A - Decomposition Method](https://senecalearning.com/en-gb/revision-notes/teacher-cpd/cpd-a-compendium-of-mathematical-methods-seneca-certified/2-1-1-method-a-decomposition-method.md)
- Next topic: [2.1.3 Method C - Expanded Form Method](https://senecalearning.com/en-gb/revision-notes/teacher-cpd/cpd-a-compendium-of-mathematical-methods-seneca-certified/2-1-3-method-c-expanded-form-method.md)

## CPD: A Compendium of Mathematical Methods (By Jo Morgan) contents

### 1 Course Overview
- 1.1 Course Structure & Commonly Asked Questions
  - [1.1.1 Introduction to the Course & Common Questions](https://senecalearning.com/en-gb/revision-notes/teacher-cpd/cpd-a-compendium-of-mathematical-methods-seneca-certified/1-1-1-introduction-to-the-course-and-common-questions.md)

### 2 Subtraction: KS2/3
- 2.1 Subtraction Methods
  - [2.1.1 Method A - Decomposition Method](https://senecalearning.com/en-gb/revision-notes/teacher-cpd/cpd-a-compendium-of-mathematical-methods-seneca-certified/2-1-1-method-a-decomposition-method.md)
  - [2.1.2 Method B - Equal Addition Method](https://senecalearning.com/en-gb/revision-notes/teacher-cpd/cpd-a-compendium-of-mathematical-methods-seneca-certified/2-1-2-method-b-equal-addition-method.md)
  - [2.1.3 Method C - Expanded Form Method](https://senecalearning.com/en-gb/revision-notes/teacher-cpd/cpd-a-compendium-of-mathematical-methods-seneca-certified/2-1-3-method-c-expanded-form-method.md)
  - [2.1.4 Method D - Partitioning Method](https://senecalearning.com/en-gb/revision-notes/teacher-cpd/cpd-a-compendium-of-mathematical-methods-seneca-certified/2-1-4-method-d-partitioning-method.md)
  - [2.1.5 Method E - Counting-Up Method](https://senecalearning.com/en-gb/revision-notes/teacher-cpd/cpd-a-compendium-of-mathematical-methods-seneca-certified/2-1-5-method-e-counting-up-method.md)
  - [2.1.6 Method F - Constant Difference Method](https://senecalearning.com/en-gb/revision-notes/teacher-cpd/cpd-a-compendium-of-mathematical-methods-seneca-certified/2-1-6-method-f-constant-difference-method.md)
  - [2.1.7 Method G - Partial Differences Method](https://senecalearning.com/en-gb/revision-notes/teacher-cpd/cpd-a-compendium-of-mathematical-methods-seneca-certified/2-1-7-method-g-partial-differences-method.md)
  - [2.1.8 Method H - Complementary Method](https://senecalearning.com/en-gb/revision-notes/teacher-cpd/cpd-a-compendium-of-mathematical-methods-seneca-certified/2-1-8-method-h-complementary-method.md)
  - [2.1.9 Method I - Nines Complement Method](https://senecalearning.com/en-gb/revision-notes/teacher-cpd/cpd-a-compendium-of-mathematical-methods-seneca-certified/2-1-9-method-i-nines-complement-method.md)

### 3 Expanding Double Brackets: KS3/4
- 3.1 Expansion Methods
  - [3.1.1 Method A - Grid Method](https://senecalearning.com/en-gb/revision-notes/teacher-cpd/cpd-a-compendium-of-mathematical-methods-seneca-certified/3-1-1-method-a-grid-method.md)
  - [3.1.2 Method B - Each by Each](https://senecalearning.com/en-gb/revision-notes/teacher-cpd/cpd-a-compendium-of-mathematical-methods-seneca-certified/3-1-2-method-b-each-by-each.md)
  - [3.1.3 Method C - Distributive Law](https://senecalearning.com/en-gb/revision-notes/teacher-cpd/cpd-a-compendium-of-mathematical-methods-seneca-certified/3-1-3-method-c-distributive-law.md)
  - [3.1.4 Method D - Inspection](https://senecalearning.com/en-gb/revision-notes/teacher-cpd/cpd-a-compendium-of-mathematical-methods-seneca-certified/3-1-4-method-d-inspection.md)
  - [3.1.5 Method E - Column Method](https://senecalearning.com/en-gb/revision-notes/teacher-cpd/cpd-a-compendium-of-mathematical-methods-seneca-certified/3-1-5-method-e-column-method.md)
  - [3.1.6 Method F - Vertical & Crosswise](https://senecalearning.com/en-gb/revision-notes/teacher-cpd/cpd-a-compendium-of-mathematical-methods-seneca-certified/3-1-6-method-f-vertical-and-crosswise.md)