Making 10 to Add

Why ten is your friend

Ten is a very special, very friendly number. Adding to 10 is easy: 10 and 3 is 13, 10 and 5 is 15. You can almost hear the answer!

So here is a clever idea: when a sum looks hard, make 10 first, then add the rest. This trick is called the make-10 strategy, and it turns tricky sums into easy ones.

The big idea

To add two numbers, we split one of them so we can fill the other one up to 10. Then we add whatever is left over.

It works because of your number bonds to 10 — the pairs that make ten. If you know that 8 needs 2 to make 10, you are ready to use this strategy.

See it on a ten frame

Let's add 8 + 5 using a ten frame. Put 8 counters in the frame:

⚫ ⚫ ⚫ ⚫ ⚫ ⚫ ⚫ ⚫ ⬜ ⬜

There are 2 empty spaces. So take 2 from the 5 and slide them in to fill the frame. Now the frame is full — that is 10. But the 5 had 3 counters left over.

So 8 + 5 becomes 10 + 3, which is 13.

A step-by-step way

Here is the make-10 strategy in three steps:

1. Look at the bigger number. How many does it need to make 10?
2. Split the other number to give that many. Now you have 10.
3. Add the leftover ones to 10.

Worked example 1: 9 + 4

1. 9 needs 1 to make 10.
2. Split the 4 into 1 and 3. Give the 1 to the 9: that makes 10.
3. Add the leftover 3: 10 + 3 = 13.

So 9 + 4 = 13.

Worked example 2: 7 + 6

1. 7 needs 3 to make 10.
2. Split the 6 into 3 and 3. Give 3 to the 7: that makes 10.
3. Add the leftover 3: 10 + 3 = 13.

So 7 + 6 = 13.

Worked example 3: 9 + 7

1. 9 needs 1 to make 10.
2. Split the 7 into 1 and 6. Give the 1 to the 9: that makes 10.
3. Add the leftover 6: 10 + 6 = 16.

So 9 + 7 = 16.

A quick table

Sum	Make 10	Leftover	Answer
8 + 3	8 + 2 = 10	1	11
9 + 5	9 + 1 = 10	4	14
7 + 4	7 + 3 = 10	1	11
8 + 6	8 + 2 = 10	4	14

Notice the pattern: we always fill up to 10, then the leftover ones tell us the ones in the teen-number answer.

Why this strategy matters

Counting on your fingers works, but it is slow and easy to get wrong. Making 10 lets you add in your head, accurately and fast. It also helps you understand teen numbers, because every answer here is "ten and some more" — exactly like our lesson on teen numbers 11 to 19.

This is one of the most important mental-math habits you can build. You will use it for years to come.

Try it yourself

You need a ten frame (or a drawn box of 10 spaces) and about 20 counters.

1. Choose a sum like 8 + 4. Put 8 counters in the frame and 4 to the side.
2. Count the empty spaces. Move that many counters in to fill the frame. Say "Ten!"
3. Count the counters still outside. Say "...and 2 more is 12!"
4. Try several sums. Each time, fill the ten first, then add the rest.
5. Challenge: Try a sum without the counters — just picture the ten frame in your head.

What's next?

Now that you can bridge through ten, you are ready for bigger adding. Try our lesson on addition and subtraction to keep practising.