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Number line addition: a quick refresher

a number line on table top with text "A quick quide to number line addition"

Want to help your child with number line addition but need a quick refresher? Here’s a quick ‘how-to’ to get you started.

If you have a child of kindergarten age, it won’t be long before they’re introduced to the math concept of addition.

To start with, they’ll explore how numbers can be joined together to make other numbers, with lots of hands-on practice using things like counters and blocks.

Before long, they’ll move on to other strategies and methods for adding.

One of those is adding numbers using a number line.

If you want to help your child with some practice at home, but aren’t sure about addition using a number line yourself, then don’t worry.

This post will show you how to add using a number line and give you some pointers for how to help your child too.

So without further ado, let’s get going. First of all, some basics…

What is a number line?

Well, the name pretty much says it all. It’s a line (usually horizontal) with numbers marked on at evenly spaced intervals. If your child is just starting out with math, it’s likely they’ll start with a number line up to 10, like so:

number line 0 - 10 with arrows showing numbers getting bigger as you move left to right, and numbers getting smaller right to left.

Here you can see that the numbers increase by 1 if you follow them to the right.

If you follow the numbers to the left, they decrease by 1, down to 0.

Before you get started adding numbers, it’s worth just taking time to look at the number line together with your child so they can see how it works.

Before too long your child will be both adding and subtracting on a number line, so it’s crucial they know which direction to move in for each operation.

Ask them: “As we go along the number line, what is happening to the numbers? Are they getting bigger or smaller?”.

You can also ask a few questions to get them thinking too, such as:

  • What’s the smallest number on the number line?
  • Whats the biggest number on the line?
  • Can you point to the number 7 on the number line? (or the number 10 or 3 or whatever..)
  • Can you find your age on the number line?

When your child is familiar with the number line and what it does, it’s time to move on to adding numbers.

How to do addition using a number line

The easiest way to show you how to add on a number line is by using some examples.

Example 1

For our first example, let’s say we want to find the answer to 4 + 3.

We’ll start by finding the number 4 on the number line.

a number line (0 to 10) showing the number 4 circled.

Next, we will add 3.

To do this, we start at the number 4, and hop along the number line 3 times to the right.

A number line (0 to 10) showing 3 hops from 4 to 7

We land at the number 7, so this tells us that 4 + 3 = 7.

Number line (0 to 10) show 3 hops from 4 to 7, with the number 7 circled.

Important!

The important thing to note here is that you count the hops along the number line. (This is why you will often see number lines being explained with help of things like frogs, kangaroos or indeed anything that jumps – it helps children remember to count the hops along the number line when adding and subtracting). Sometimes, children will try to count the number they start on as ‘one’. Don’t! Only count the hops.

Example 2:

Let’s look at another example, say 6 + 4.

If we want to find the answer to 6 + 4, we first need to find 6 on the number line.

A number line (0 to 10) with the number 6 circled.

Then, to add 4, we will hop 4 times to the right and see where we land.

Number line with 4 hops from 6 to 10

We land on the number 10 so that tells us that 6 + 4 = 10.

Number line with 4 hops from 6 to 10, with the number 10 circled.

And the cool thing about addition is….

One thing that’s great to show your child when adding numbers is that the order of the two addends (the numbers you’re adding together) doesn’t matter. When it comes addition, the order of the numbers can be swapped around.

Let me show you:

Let’s take 5 + 4 as an example

If we start at the number 5 and hop 4 times along the number line, we reach the number 9.

This tells us that 5 + 4 = 9.

Number line showing 4 hops from 5 to 9

Let’s now swap the order of the addends around. This time, instead of 5 + 4, we will calculate 4 + 5.

We will start at the number 4 and hop 5 times along the number line. We still land on the number 9.

Number line showing 5 hops, from 4 to 9

This shows us that 5 + 4 and 4 + 5 both equal 9.

The order of the 4 and 5 can be swapped around and yet the answer is still the same.

How to add three 1-digit numbers using a number line

Once your child has mastered adding two numbers, they can even try adding 3 numbers together.

The method is exactly the same, there is just one extra number to add.

Let’s look at an example, say 3 + 6 + 2.

For this example, we’ll be using a number line that goes up to 15.

Let’s start by finding the number 3 on the number line.

3 highlighed on number line

Next, we’ll add 6 by hopping along the number line to the right 6 times. This lands us at 9.

6 hops along line from 3 to 9

We have one more number to add: 2. Let’s hop 2 more times to the right, starting at 9.

6 hops in yellow from 3 to 9 and two hops in blue from 9 to 11

And we land at the number 11.

8 hops along in total, from 3 to 11, with 11 circled as the final answer

So this tells us that 3 + 6 + 2 = 11.

And remember, just as before, the numbers can be added in any order.

The three numbers ( 3, 6 and 2) can be added in any order and your answer will still be 11.

So there we have it! A quick how-to for adding numbers using a number line. I hope you found it helpful.

Psst… Before you go, have you seen our Kindergarten Number Pack? It features a whole section on addition within 10 as well as subtraction too:

KINDERGARTEN NUMBER PACK

If you liked this number line addition post or want to save it for later, why not pin it? Thanks for your help!

Number line on wooden table with text 'how to add numbers using a number line'.

More kindergarten math posts from Math, Kids and Chaos:

Or simply head back to our kindergarten math page for a whole selection of resources and activities just for kindergarten.

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