A Guide to Number Bonds

Your child’s homework on "number bonds" looks familiar – but the language is different to what you learned at school and you're concerned your help will be wrong or confusing. It happens to us all!

What are number bonds?

Number bonds are also known as addition and subtraction facts, facts families, and doubtless other names too. They're simply combinations of numbers that fit together.

What do children need to know?

Children must know the number bonds that make 10. 

10 can be made up out of:

  • 1 and 9

  • 2 and 8

  • 3 and 7

  • 4 and 6

  • 5 and 5

The feature video at the very top of this article shows all the addition number bonds to 10.

These addition bonds to 10 are naturally related to the subtraction bonds to 10 as seen in this video:

If children have instant recall of each of these number bonds and all the ways they can fit together, they’ll be well on the way to dealing with equations confidently and quickly. Ideally, they’ll also know their number bonds to 4, 5, 6, 7, 8 and 9.

Once your child has mastered these, the number bonds for numbers up to 20 are also useful to know – immediately knowing that (for example) 17 is made up of 8 and 9 makes subtraction much less stressful.

Number bonds the Singapore math way

This video shows number bonds using the concept of "whole and parts" - an idea that comes from the Singapore math program.

Why are they important?

Knowing your number bonds fluently up to ten is one of the foundations to more complex math such as adding and subtracting with the ‘column methods’ as well as mental addition and subtraction to 100 and beyond.

They also help with addition and subtraction bridging 10. If you want to work out 16 – 8,  for example, you can use the following thought process:

  • 8 is made up of 6 and 2

  • 16 – 6 is 10, that’s easy

  • 10 is made of 8 and 2

  • 10 – 2 is 8

  • So 16 – 8 = 8

In summary

Even if the new language used to describe math is unfamiliar to you, the operations won't have changed since you and I were at school. Whether you know them as number bonds, number fact families, or anything else, you can still help your child to learn them and build a strong foundation for the more advanced math he or she will be learning soon.



I’m Ged, Co-founder of Komodo, ex-math teacher, and dad. If you have any questions please get in touch.

About Komodo – Komodo is a fun and effective way to boost elementary math skills. Designed for 5 to 11-year-olds to use in the home, Komodo uses a little and often approach to learning math (15 minutes, three to five times per week) that fits into the busy routine. Komodo helps users develop fluency and confidence in math – without keeping them at the screen for long.

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