Counting within 20

Counting on to and back from 20

When you count to 20, you start at 1 (or zero) and count on until you reach 20.

Each number is one more than the last.

When you count back from 20, you start at 20 and count back until you reach 1 (or zero).

Each number is one less than the last.

You can use number lines like the one below to help you learn how to count on and count back.

Quiz: Counting on and back

Test out your knowledge of counting on to and back from 20 with this quiz, then read on to complete the page.

Numbers from 11 to 20

All the numbers between 10 and 20 are made up of 1 ten and different amounts of ones. The number 20 is made up of two tens.

In the images below, the tower of blue blocks represents ten, and the red blocks represent different amounts of ones.

Can you see how, when added together, they equal the number shown next to the blocks?

Using a number line to count on and back

Here are the numbers 1 to 20 shown on a number line.

You can use a number line to help you count on. You may already know the order the numbers go in.

You count on by one to find which number is one more than the last.

Counting back from 20 can be a little bit trickier than counting on.

Each number is one less than the number before.

You might like to use a number line to help you count back.

You count back by one to find which number is one less than the last.