What is subtraction?
Subtraction has two main meanings:
- Take away: You have 12 balloons and 5 float away. How many are left? 12 − 5 = 7.
- Compare: You have 12 stickers and your friend has 5. How many more do you have? The difference is 7.
Both are written with the minus sign: 12 − 5 = 7.
Words that tell you to subtract include left, take away, fewer, how many more, difference and minus.
Ways to subtract
1. Take away objects. Put out 12 counters, remove 5, and count what is left.
2. Count back. Start at 12 and count back 5: 11, 10, 9, 8, 7. This works well when you take away a small number.
3. Count up. To find 12 − 9, count up from 9 to 12: 10, 11, 12. That’s 3 steps, so the answer is 3. Counting up is best when the two numbers are close together.
4. Number line. Start at 12 and jump 5 to the left. You land on 7.
5. Think addition. If you know 5 + 7 = 12, then you know 12 − 5 = 7.
Order matters!
Unlike addition, you can’t swap the numbers. 12 − 5 = 7, but 5 − 12 is a very different question. In early maths, put the bigger number first.
Fact families
Three numbers that work together make a fact family. With 5, 7 and 12:
| Addition | Subtraction |
|---|---|
| 5 + 7 = 12 | 12 − 5 = 7 |
| 7 + 5 = 12 | 12 − 7 = 5 |
If you know one fact, you know all four.
Worked examples
Example 1: 12 − 5 = ?
Count back 5 from 12: 11, 10, 9, 8, 7. Answer: 7.
Check: 7 + 5 = 12. ✓
Example 2: There are 9 birds on a fence. 3 fly away. How many are left?
9 − 3 = 6 birds.
Example 3: Ben has 10 marbles. Ava has 6. How many more does Ben have?
Compare: 10 − 6 = 4 more.
Common mistakes
- Counting the starting number when counting back. For 12 − 5, start saying "11", not "12".
- Swapping the numbers so you subtract the wrong way round.
- Not checking. Add your answer to the amount taken away; you should get back to the starting number.
Try it yourself
- 8 − 3 =
- 10 − 4 =
- 15 − 13 =
- A plate has 7 cookies. You eat 2. How many are left?
- Write the fact family for 3, 4 and 7.
Answers: 1) 5 2) 6 3) 2 4) 5 5) 3 + 4 = 7, 4 + 3 = 7, 7 − 3 = 4, 7 − 4 = 3
Quick recap
- Subtraction means take away or find the difference.
- Count back for small amounts; count up when numbers are close.
- Check with addition: the fact family connects them.