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Number bonds to 20: a guide for parents and teachers
Number bonds are pairs of numbers that add up to a given total. 7 and 3 are a number bond to 10; 12 and 8 are a number bond to 20. Knowing them instantly, without counting on fingers, is one of the most useful things a young child can learn in maths, because almost every later calculation leans on them.
When do children learn number bonds?
In England, the National Curriculum asks pupils in Year 1 (age 5 to 6) to represent and use number bonds and related subtraction facts within 20. In Year 2 they should recall and use addition and subtraction facts to 20 fluently, and derive related facts up to 100. In practice, most children secure bonds to 10 first, then extend them to 20.
Number bonds to 10
There are only six pairs to learn: 0 + 10, 1 + 9, 2 + 8, 3 + 7, 4 + 6 and 5 + 5. Each one also gives two subtraction facts, so 3 + 7 = 10 tells you that 10 − 7 = 3 and 10 − 3 = 7.
Number bonds to 20
Bonds to 20 build straight on bonds to 10. If a child knows 3 + 7 = 10, they can see that 13 + 7 = 20, and that 3 + 17 = 20. It's worth making that link explicit, because it turns eleven new facts into a pattern they already know.
How to practise number bonds
Little and often. Two or three minutes a day works far better than a long weekly session. A quick question in the car or while laying the table counts.
Use objects first. Ten counters, a ten-frame or fingers help children see that 6 and 4 make 10 before they're asked to remember it.
Go both ways. Ask "what goes with 6 to make 10?" as often as "what is 6 + 4?". Missing-number questions build real understanding.
Spot them in the wild. Puzzles where a child has to find the bond, rather than just answer a sum, make them scan and compare numbers, which is exactly the fluency teachers are looking for.
A honeycomb game for number bonds
In a Beequation puzzle, one number in the honeycomb is made by adding two of the others. To solve it, children test pairs and check totals, which is number-bond practice in disguise. Can you find it in this one?
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10, because 7 + 3 = 10.Once children are confident, the same game moves on to bonds to 20 and beyond:
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20, because 13 + 7 = 20.Our free printable puzzle pack has twelve of these for sums to 20, with an answer key, and Beequation Kids starts with sums to 10 for five-year-olds, with Indie the bee giving a gentle hint when a child gets stuck.
Quick answers
How many number bonds to 20 are there? Counting 0 + 20 and both orders as one pair, there are 11: 0 + 20, 1 + 19, 2 + 18 and so on up to 10 + 10.
Should children count on their fingers? At first, yes: it builds understanding. The aim is to move from counting to recall, so keep practising until the answer comes without counting.
Try a Beequation puzzle
Every honeycomb hides one number made from two others. It's free in your browser, with levels for children aged 5 to 12 and for adults.