# What is a number sentence?

### What is a number sentence?

A number sentence is an arrangement of numbers and symbols, such as the following:

**6 + 7 = 13
45 - 6 = 39
8 x 9 = 72
48 ÷ 8 = 6**

There was a time when teachers would refer to the word 'sum' when using any of the above, but this is confusing for children, as the word 'sum' is a term that should only be used when talking about addition.

**Children start learning how to write addition and subtraction number sentences in Year 1.** They will probably start learning about addition by making two groups (for example: 5 bananas and 2 apples) and putting them together. They then develop towards working out how to write these numbers and arrange them with the symbols + and = to make a number sentence that makes sense.

**In Year 2, children start to write number sentences for multiplication and division**, so they need to understand the symbols: x and ÷ and be able to write them.

### Working with number sentences in the classroom

At any time in Key Stage 1 or 2, teachers may show children a word problem and then ask them to write the number sentence that goes with it, for example:

*I have a £5 note. I spend £3.20. How much money do I have left?*

On showing children this problem, a teacher would probably ask what operation the children need to do: add, subtract, multiply or divide? They may then ask them to write out the number sentence that they will be carrying out to work out the problem, which would be:

*£5 - £3.20 =*

Children may also come across number sentences with gaps in them. In Key Stage 1 they may come across something like this:

and be asked to work out what goes in the gap.

These will get progressively harder in Key Stage 2, for example:

Sometimes children will be given number sentences where there are two operations on each side, for example:

Here, they need to understand that since the left hand side equals 16, the right hand side has to equal the same amount, since 20 - 4 = 16, the number in the gap should be 4.

They may be given a number sentence like the one above, but where there is not one answer to put in the gap:

Here, it may be a good idea to try a number out in the first gap, for example, 10:

**10 + 20 + 10 = 40**

We know that 5 x 8 = 40, so 8 could then go in the other gap.

A teacher may then ask children to find as many other possibilities as they can.