Number bonds for subtraction

Quick answer

You can use number bonds to help you solve subtraction problems quickly. If you know that 5 + 3 = 8, then you also know that 8 - 3 = 5 and 8 - 5 = 3.

Learning outcome

By the end of this page, you will be able to use number bonds to solve subtraction problems in your head, without needing to count on your fingers or use a calculator.

Success signs:

• You can quickly say the subtraction facts when you know the addition fact.
• You can solve subtraction problems by thinking about what number goes with a given number to make a total.
• You can use number bonds to check if your subtraction answer is correct.
• You can explain how number bonds help you solve subtraction problems.

Why this matters

Knowing number bonds helps you become faster and more confident with subtraction. It's like having a secret helper that makes maths easier. When you know that 7 + 3 = 10, you can quickly solve 10 - 3 = 7 or 10 - 7 = 3. This skill is useful in many situations, like sharing toys, counting money, or solving word problems in your maths book.

In games and real life, you often need to think quickly about how numbers fit together. For example, if you have 12 sweets and eat 5, you can quickly work out that you have 7 left by using number bonds. This makes you a maths superstar!

How it works

Number bonds show how numbers can be split into parts. When you know one addition fact, you automatically know two subtraction facts.

Here’s how it works:

1. Find an addition fact you know well, like 4 + 6 = 10.
2. Now you know that 10 - 6 = 4 and 10 - 4 = 6.
3. Try it with different numbers to see the pattern.

Think of it like a triangle of numbers. If you know two numbers, you can always find the third one.

Examples you can see

Let’s look at some examples using number bonds for subtraction:

Try drawing these as triangles:

For 3 + 7 = 10:

Draw a triangle with 3 at the bottom left, 7 at the bottom right, and 10 at the top.

Now you can see that:

• 10 - 7 = 3
• 10 - 3 = 7

Try it as a mini adventure

Imagine you are a treasure hunter! You have found a treasure map that shows you how many coins are in each chest. You need to solve subtraction problems to find out how many coins are left after some are taken.

Adventure Quest:

1st time: You find a chest with 9 coins. You take 4 coins. How many coins are left?

2nd time: You find another chest with 12 coins. You take 5 coins. How many coins are left?

3rd time: You find a chest with 8 coins. You take 3 coins. How many coins are left?

4th time: You find a chest with 15 coins. You take 9 coins. How many coins are left?

5th time: You find a chest with 7 coins. You take 2 coins. How many coins are left?

How to solve:

Use your number bonds! For 9 - 4, think: What number plus 4 makes 9? That’s 5. So 9 - 4 = 5.

For 12 - 5, think: What number plus 5 makes 12? That’s 7. So 12 - 5 = 7.

Try solving the rest yourself using number bonds!

Common mistakes

• Mistake: Thinking that 10 - 3 = 7 and 10 - 7 = 3, but getting confused about which number goes where.
• Why it happens: Not understanding that the two smaller numbers in an addition fact become the two subtraction facts.
• Fix: Draw the triangle number bond to see the relationship clearly.

• Mistake: Forgetting that subtraction is not commutative, so 10 - 3 ≠ 3 - 10.
• Why it happens: Mixing up addition and subtraction facts.
• Fix: Remember that subtraction means taking away, so the bigger number goes first.

• Mistake: Using a calculator or counting on fingers when you could use number bonds.
• Why it happens: Not trusting your mental maths skills.
• Fix: Practice number bonds daily until they feel easy and quick.

Parent and carer guide

Help your child learn number bonds for subtraction by:

1. Using everyday situations like sharing snacks or counting toys to show how number bonds work.
2. Playing games where you say an addition fact and your child says the subtraction facts.
3. Using visual aids like number lines or counters to make the connection clear.
4. Encouraging your child to explain their thinking so you can see if they really understand.
5. Practicing regularly but not for long sessions – 5-10 minutes daily works best.

Don’t worry if your child makes mistakes – that’s how they learn. Keep it fun and celebrate small wins!

Practice questions

1. What is 10 - 6?
2. What is 15 - 8?
3. What is 12 - 5?
4. What is 9 - 4?
5. What is 14 - 7?
6. What is 11 - 3?
7. What is 13 - 6?
8. What is 8 - 2?
9. What is 16 - 9?
10. What is 10 - 7?

Answers:

1. 4
2. 7
3. 7
4. 5
5. 7
6. 8
7. 7
8. 6
9. 7
10. 3

FAQ

What are number bonds?

Number bonds are pairs of numbers that add up to a given total. For example, 5 and 3 are number bonds for 8 because 5 + 3 = 8.

How do number bonds help with subtraction?

When you know one addition fact, you automatically know two subtraction facts. For example, if you know 6 + 4 = 10, then you also know 10 - 4 = 6 and 10 - 6 = 4.

Can I use number bonds for bigger numbers?

Yes! Number bonds work for any numbers. For example, 25 + 15 = 40, so 40 - 15 = 25 and 40 - 25 = 15.

Why should I learn number bonds for subtraction?

Number bonds make subtraction faster and easier. They help you solve problems quickly in your head and build a strong foundation for more advanced maths.

How can I practice number bonds at home?

You can practice by playing games, using counters or blocks, drawing number bond triangles, or solving everyday subtraction problems like “If you have 10 apples and eat 3, how many are left?”