---
title: "Addition and subtraction strategies (age 7+)"
description: "Explain why addition and subtraction strategies work, using place value and the properties of operations"
canonical: https://lightmysky.com/learn/mathematics/addition-and-subtraction-strategies-age-7-mt_zxST3MarI9
source: https://lightmysky.com/learn/mathematics/addition-and-subtraction-strategies-age-7-mt_zxST3MarI9.md
retrieved: 2026-10-19
---

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# Addition and subtraction strategies (age 7+)

Explain why addition and subtraction strategies work, using place value and the properties of operations

Subject: Mathematics · Area: Addition & Subtraction · Ages 7 to 8
Page: https://lightmysky.com/learn/mathematics/addition-and-subtraction-strategies-age-7-mt_zxST3MarI9

## Ready when they can

- Explain why adding tens and ones separately gives the correct total
- Describe why a compensation strategy works (e.g. 'I added 1 too many, so I subtract 1')
- Use place-value language to justify a written method step by step

## Lesson: Why splitting numbers works

When you add two numbers like 67 and 24, you can split each one into tens and ones, add the tens together, add the ones together, then join the two answers. This works because of place value: the tens digit always means 'how many tens' and the ones digit always means 'how many ones,' so tens only ever combine with tens, and ones only ever combine with ones.

*(drawing: 67 + 24: hop +20 for the tens, then hop +4 for the ones. You land on 91.)*

**Example.** Look at 67 + 24. Split it into 60 + 20 and 7 + 4. 60 + 20 = 80. 7 + 4 = 11. Now join them: 80 + 11 = 91. Splitting works because 60 and 20 are both tens, and 7 and 4 are both ones, so nothing gets mixed up.

**Tip.** Compensation is another good strategy. For 29 + 15, you might add 1 to 29 to make 30, because 30 is easier to work with. But adding that 1 changes the total, so you must take it back off at the end: 30 + 15 = 45, then 45 minus 1 = 44. Whatever extra you add, you must remove later.

**Recap.** Splitting and compensation both work because they keep track of place value, so the total stays exactly right.

## Practice

16 questions on this page, each with its working shown.

## Needs first

- [The three digits of a three-digit number](https://lightmysky.com/learn/mathematics/the-three-digits-of-a-three-digit-number-mt_aPBzD28_mT)
- [Fluent adding and subtracting within 100](https://lightmysky.com/learn/mathematics/fluent-adding-and-subtracting-within-100-mt_cChv2j_-Da)
- [Addition and subtraction strategies](https://lightmysky.com/learn/mathematics/addition-and-subtraction-strategies-mt_PpWSHA-0kv)

## Opens up

- [Justifying mathematical reasoning](https://lightmysky.com/learn/mathematics/justifying-mathematical-reasoning-mt_pyMD_SIiYO)