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addition

Checking addition with subtraction

Use inverse operations to see whether an answer makes sense.

Quick answer

You can check if your addition is correct by using subtraction. If you add two numbers together and then subtract one of them, you should get the other number.

Learning outcome

By the end of this page, you will be able to check if your addition answers are correct using subtraction. Success signs:
  • You can add two numbers together
  • You can subtract one number from the total
  • You get the other original number
  • You can use this to check your work

Why this matters

Checking your work helps you catch mistakes and feel more confident about your answers. It's like having a detective helper who makes sure your maths is right. This skill will help you in school tests, when you're shopping, and when you're solving puzzles or playing games where numbers matter.

How it works

Let's look at how to check addition with subtraction step by step:
  1. First, you add two numbers together
  2. Then, you take one of the numbers you added and subtract it from the total
  3. If your answer matches the other number you started with, your addition was correct!
Here's how it looks in a simple example:
  • Let's say you add 5 + 3 = 8
  • To check this, you take one number (like 5) and subtract it from the total (8)
  • So 8 - 5 = 3
  • Since 3 matches the other number you started with, your addition was correct!

Examples you can see

Let's look at some clear examples to understand how this works: Example 1:
  • 5 + 7 = 12
  • Check: 12 - 5 = 7
  • Yes! 7 is the number we started with, so the addition is correct.
Example 2:
  • 11 + 4 = 15
  • Check: 15 - 11 = 4
  • Yes! 4 is the number we started with, so the addition is correct.
Example 3:
  • 8 + 9 = 17
  • Check: 17 - 8 = 9
  • Yes! 9 is the number we started with, so the addition is correct.
Example 4:
  • 6 + 6 = 12
  • Check: 12 - 6 = 6
  • Yes! 6 is the number we started with, so the addition is correct.

Try it as a mini adventure

Adventure: The Magic Number Garden You are a gardener who has planted some flowers. You have 7 red flowers and 5 blue flowers. You want to make sure you counted them all correctly!
  1. First, you add them together: 7 + 5 = 12 flowers
  2. Then, you check your work: 12 - 7 = 5 flowers
  3. Great! You have 5 blue flowers, which matches what you started with
  4. Now you know your counting was right!
Let's try another one:
  1. You have 9 yellow flowers and 3 purple flowers
  2. Add them: 9 + 3 = 12 flowers
  3. Check: 12 - 9 = 3 flowers
  4. Perfect! You have 3 purple flowers, so your counting was right!
Mini Challenge: Try this with your own objects at home. Count 6 toys and 4 books, add them together, then check with subtraction.

Common mistakes

  • Mistake: Adding wrong numbers together
    • Why it happens: Sometimes children get confused about which numbers to add
    • Fix: Double-check the numbers you're adding by reading them carefully
  • Mistake: Subtracting the wrong way
    • Why it happens: Children might forget which number to subtract from the total
    • Fix: Always subtract the first number you added from your total
  • Mistake: Not checking the answer properly
    • Why it happens: Children might quickly say "yes" without really checking
    • Fix: Take a moment to make sure your subtraction gives you the right number
  • Mistake: Thinking that checking means doing the same addition again
    • Why it happens: Children might think checking is just repeating the problem
    • Fix: Remember that checking uses subtraction, not addition!

Parent and carer guide

Here's how you can help your child learn to check addition with subtraction:
  1. Start with simple examples using objects like toys, buttons, or pasta pieces
  2. Practice with your child: "What is 4 + 3? Now let's check: what is 7 - 4?"
  3. Use everyday situations: "We had 5 cookies and ate 2. How many are left? Check by adding 2 + 3"
  4. Encourage your child to say the checking step out loud
  5. Don't worry if they make mistakes at first - it's all part of learning!
  6. Make it fun: create silly stories or use games to practice
  7. Be patient - this skill takes time to master
  8. Remember to celebrate when your child gets it right!

Practice questions

  1. 5 + 8 = 13. Check: 13 - 5 = ?
  2. 6 + 9 = 15. Check: 15 - 6 = ?
  3. 3 + 7 = 10. Check: 10 - 3 = ?
  4. 12 + 4 = 16. Check: 16 - 12 = ?
  5. 10 + 5 = 15. Check: 15 - 10 = ?
Answers:
  1. 8
  2. 9
  3. 7
  4. 4
  5. 5

FAQ

What is inverse operation?

Inverse operations are opposite actions. Addition and subtraction are inverse operations because one undoes the other.

Why do we need to check our addition?

Checking helps us make sure we didn't make mistakes. It's like double-checking your homework to be extra sure!

Can I use this with bigger numbers?

Yes! You can check any addition, even with large numbers. The same method works the same way.

What if my subtraction doesn't give me the right number?

If your subtraction doesn't match, it means your addition might be wrong. You should double-check your original addition.

Is checking addition with subtraction the same as doing addition again?

No! Checking uses subtraction, not addition. It's like checking your work by looking at it from a different angle.