# Count in 10s

## Learning focus

Learn how to count in tens from 0 to 100.

This lesson includes:

- one video
- a learning summary
- one activity

# Learn

Begin by watching the video below. It will remind you how to count up and down in 10s.

For more help and advice with Maths watch this Teacher Talk video.

Here is a number grid from 1 to 100.

Look at the coloured numbers. What do you notice?

Here are the numbers:

10, 20, 30, 40, 50, 60, 70, 80, 90, 100

Each number is **10 more than** the one before.

Let's use counting in tens to find the answers to some questions.

## Example 1:

Here is a pile of 10 books.

**Can you count in tens to find how many books there are in 4 piles?**

Let's count them:

10, 20, 30, 40

You can see that there are 40 books in 4 piles of 10.

You can also write this as a repeated addition.

10 + 10 + 10 + 10 = 40

**How many piles would there be if you had 70 books?**

Count in 10s to help you:

10, 20, 30, 40, 50, 60, 70

You would have 70 books in 7 piles of 10.

You can also write this as a repeated addition.

70 = 10 + 10 + 10 + 10 + 10 + 10 + 10

## Top tip

Instead of counting up in 10s, you can **multiply by 10**, which is a more efficient way of doing the same calculation.

So, 7 piles of 10 books is the same as saying:

7 x 10 = 70 books

Counting in 10s gives you the 10 times table.

## Example 2:

This array has 10 apples in each row.

There are 3 rows, making 3 lots of 10.

How many apples are there altogether? Let's count the rows in tens:

10, 20, 30

There are 30 apples in the array.

Can you write this as a repeated addition?

10 + 10 + 10 = 30

Can you write this as a multiplication?

3 lots of 10 is the same as 3 x 10 = 30

## Example 3:

**A box of pencils holds 10 pencils.**

**Can you count in tens to work out how many there are in total?**

Let's count them:

10, 20, 30, 40, 50, 60, 70

Through repeated addition this is:

10 + 10 + 10 + 10 + 10 + 10 + 10 = 70

Or you could do this through multiplication:

7 lots of 10 = 70

so

7 x 10 = 70

# Practise

## Activity 1

Practise counting up in tens from 0 to 100.

0 | 10 | 20 | 30 | 40 | 50 | 60 | 70 | 80 | 90 | 100 |

Remember that the last digit is always 0 when counting in 10s.

Now, have a look at these four pictures showing groups of 10s. Can you count in 10s to work out how many objects there are in each picture?

# Play

Play **Guardians: Defenders of Mathematica** to learn more about this topic and test your skills.

# There's more to learn

Have a look at these other resources.