Year 1 maths · Key Stage 1 · Number – addition and subtraction

Year 1 addition and subtraction to 20: number bonds

In Year 1 children learn that addition and subtraction are linked. They read and write number sentences using +, − and =, learn the pairs of numbers that make 10 and 20 (called number bonds), and add and subtract within 20. They solve simple word problems with objects and pictures, including missing number problems such as 7 = ? − 9. Quick recall of these facts is the foundation for all the mental calculation that follows.

Adding and subtracting within 20, explained

A number bond is a pair of numbers that make a given total: 6 and 4 make 10, and 9 and 7 make 16. Year 1 children learn the bonds to 10 until they can answer almost instantly, then use them to work within 20. Each fact is met in several forms, such as 9 + 7 = 16, 16 − 7 = 9 and 7 = 16 − 9, so children see that one fact belongs to a small family of number sentences. Many teachers use ten frames, number tracks and part-whole diagrams, where a whole is split into two parts, to show the same facts in pictures.

Children also learn to read, write and interpret statements using the plus (+), minus (−) and equals (=) signs. The equals sign is taught as “is the same amount as”, not as “the answer comes next”. That is why you will see sentences written in different shapes, such as 8 = 5 + 3. It is also the key to missing number problems like 7 = ? − 9. The part with the question mark must have the same value as 7, so the missing number is 16, because 16 − 9 = 7.

Adding and subtracting one-digit and two-digit numbers to 20 includes working with 0, and children see that adding or subtracting 0 leaves a number unchanged. Strategies taught include counting on from the larger number, making ten (for 8 + 5, take 2 from the 5 to make 10, then add the 3 that is left), using doubles such as 6 + 6, and counting back or counting up to find the difference for subtraction. “Two-digit numbers to 20” means numbers such as 14 or 17, in calculations like 14 + 3 or 17 − 5. Children are encouraged to choose the method that suits the numbers.

Word problems use a set vocabulary: put together, altogether, total, take away, distance between, difference between, more than and less than. Subtraction is not only taking away. A question such as “Tom has 12 stickers and Mia has 7, how many more has Tom?” asks for the difference, which children can find by counting up from 7 to 12. Children first act problems out with objects, then draw them, and only then write the number sentence. Being able to say which operation fits a story is just as important as getting the answer.

Words your child will hear

Number bond: A pair of numbers that make a total. 3 and 7 are a number bond to 10.
Altogether and total: Words that tell you to add: how many are there when two groups are put together?
Take away: Remove some from a group to see how many are left. 12 take away 5 leaves 7.
Difference: How much bigger one number is than another. The difference between 7 and 12 is 5.
Part and whole: The whole is the total. The parts are the smaller numbers that make it up, such as 9 and 7 for 16.
Make ten: A strategy: split one number so that part of it fills up a ten, then add the rest.
Number sentence: A calculation written with signs, such as 9 + 7 = 16.

What the National Curriculum says

In Year 1, pupils should be taught to:

Read, write and interpret mathematical statements involving addition (+), subtraction (−) and equals (=) signs
Represent and use number bonds and related subtraction facts within 20
Add and subtract one-digit and two-digit numbers to 20, including 0
Solve one-step problems that involve addition and subtraction, using concrete objects and pictorial representations, and missing number problems such as 7 = ? − 9

Objectives from the National Curriculum in England, © Crown copyright, used under the Open Government Licence v3.0.

A worked example

There are 9 ducks on the pond and 7 more swim over. How many ducks are there altogether? Then write the facts that go with it.

“More swim over” and “altogether” tell us to add. The number sentence is 9 + 7 = ?
Counting on 7 from 9 is slow and easy to get wrong, so use the make ten strategy. 9 needs 1 more to make 10, so split 7 into 1 and 6.
```
9 + 7
= 9 + 1 + 6
```
Add the 1 to the 9 to make 10, then add the 6 that is left.
```
9 + 1 = 10
10 + 6 = 16
```
Check with a ten frame. One frame is full with 10 counters and a second frame holds 6. That is 16 counters.
Now write the family of facts. The parts are 9 and 7, and the whole is 16. For the missing number problem 7 = ? − 9, ask: what, when 9 is taken away, leaves 7? It is 16.
```
9 + 7 = 16
7 + 9 = 16
16 − 7 = 9
16 − 9 = 7
7 = 16 − 9
```

There are 16 ducks. 9 + 7 = 16, so 16 − 7 = 9 and 16 − 9 = 7.

Common mistakes and how to help

Reading the equals sign as “the answer comes next”

Most sums children meet look like 3 + 4 = 7, so they decide that = means “make the total”. A sentence such as 7 = ? − 9, or 5 + 3 = ? + 4, then makes no sense to them.

What helps: Say “is the same as” whenever you read it. Use a pair of balance scales, or two matching piles, to show that both sides must have the same amount. Write some number sentences back to front, such as 8 = 5 + 3.

Being one out when counting on, so 8 + 5 comes out as 12

The child says “8” as the first of their five counts instead of starting after it: 8, 9, 10, 11, 12 uses only four more numbers.

What helps: Hold the 8 in your head, then put up one finger per number added: 9, 10, 11, 12, 13. Better still, move towards the make ten strategy, which avoids counting in ones.

Thinking subtraction is only “taking away”, so “how many more?” is confusing

Most early subtraction stories remove things from a group. Difference problems involve comparing two groups, so a child may add 12 and 7 because “more” sounds like adding.

What helps: Line up the two groups side by side, one object against another, and look at what is left unmatched. Counting up from 7 to 12 also gives the difference, 5.

Swapping the numbers in a subtraction, as if 5 − 9 were the same as 9 − 5

In addition 3 + 8 and 8 + 3 give the same answer, so children expect subtraction to work in either order too.

What helps: Use objects: you can take 5 away from 9 counters, but you cannot take 9 counters away from a pile of 5. Contrast this with adding, where 5 + 9 and 9 + 5 are the same. Always start a subtraction story with the starting amount.

How to help at home

Hide and find. Put 10 spoons or toy cars on the table, cover some with a cup and show the rest. “I can see 6, so how many are hidden?” It is the number bond to 10 in a game, and you can change the total to 12 or 15 as your child grows in confidence.
Dominoes and dice. Count the dots on each half of a domino and say the sum, then the matching subtraction: 5 and 4 make 9, so 9 take away 4 leaves 5. Two dice make totals up to 12, which is good practice for bonds and doubles.
Tell stories with the sentences. Make up a short story for 12 − 5, such as “12 biscuits and 5 get eaten”, then another for the difference, “Ali has 12 and Bea has 5, how many more does Ali have?” Ask your child to say which signs would match.
Shop with small coins. Set out items priced at 1p to 10p with real coins. “The pencil costs 6p and the rubber costs 8p, what is the total?” Keep to totals within 20 and let your child pay with 1p coins they can count.
Write the family of facts. When your child knows one fact, ask for the other three, for example 6 + 8 = 14, 8 + 6 = 14, 14 − 6 = 8 and 14 − 8 = 6. Writing them on a strip of paper, or on the pavement in chalk, makes the link easy to see.

Leads on to

Year 2: Adding and subtracting to 100

Everything in Year 1 maths

Updated 20 October 2026.