
What is a number line?
A number line is a straight line with numbers written in order from lowest to highest.
Number lines can go up to any number, such as 10, 20, or even more!
They help you to see where each number belongs and can be useful when adding and subtracting.

Activity: Number lines
Complete this interactive activity to understand number lines. Then put your knowledge to the test.
Using a number line
This is a number line.

This number line starts at 0 and ends at 10. As you move along the number line, the numbers go up in ones.
0 is the smallest number and 10 is the largest.
The number 5 is halfway between 0 and 10.
Number lines can help you to add and subtract.
Adding numbers in different orders
When you are adding, it doesn't matter which order you put the numbers in the answer will always be the same.
Look at this number line and these blocks.

Use the number line to find the answer to:
2 + 5 =
Now try it this way:
5 + 2 =
Which way was the easiest?
You probably found 5 + 2 was the easiest way to add.
It is always easiest to put the largest number first when adding.
Example 1

Here is a number line, which starts at 0 and goes up to 10.
Which numbers are larger than 8?
✓ 9 and 10 are larger than 8.

Going forward on the number line, each number is one more than the last.
9 is one more than 8.
10 is two more than 8.
10 is the largest number on this number line.
Example 2

If you have 3 red apples and 2 green apples, how many apples are there altogether?
✓ There are 5 apples altogether.
Find 3 on the number line. Then count up by 2.
You can use your finger to help count on the line.
3 + 2 = 5

Example 3

If you have 9 apples and then eat 4 of the apples, how many apples will you have left?
✓ You will have 5 apples.
Find 9 on the number line. Then count down by 4.
You can use your finger to help count on the line.
9 - 4 = 5

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