Using a Number Line
An early-years lesson on the number line: read it, count on and back, jump to add and subtract, find numbers between, with worked examples and a quiz.
Key takeaways
- A number line is a straight line with numbers marked in order from left to right.
- Numbers get bigger as you move RIGHT and smaller as you move LEFT.
- To add, jump to the right; to subtract, jump to the left.
- The number line helps you count on, count back, and find numbers that come between.
What is a number line?
A number line is a straight line with numbers marked on it in order. Picture a path with stepping stones, each stone labelled with a number: 0, 1, 2, 3, 4, 5… The stones are evenly spaced, so every step is the same size. The number line takes the numbers you say out loud and lays them out as a picture you can point to and travel along.
0 — 1 — 2 — 3 — 4 — 5 — 6 — 7 — 8 — 9 — 10This simple picture is one of the most useful tools in all of maths. It helps you count, compare, add and subtract — all by moving along the line.
Bigger on the right, smaller on the left
The most important rule of the number line:
- Move RIGHT → numbers get BIGGER.
- Move LEFT → numbers get SMALLER.
So 8 is bigger than 3 because it sits further to the right. And 2 is smaller than 6 because it sits further to the left. This makes the number line perfect for comparing numbers — whoever is further right is the bigger number. You can practise comparing in our lesson on more than, less than and equal.
Counting on and counting back
The number line turns adding and taking away into a game of jumps.
- Counting on (adding): start on a number and jump to the right.
- Counting back (subtracting): start on a number and jump to the left.
Each jump is one step. If you make 3 jumps, you have moved 3. This is why the number line and arithmetic fit together so well — you are walking the maths with your finger.
| Action | Direction | What it means |
|---|---|---|
| Add | jump right | make the number bigger |
| Subtract | jump left | make the number smaller |
| Compare | look across | further right = bigger |
Worked example 1: adding by jumping right
Work out 4 + 3 on the number line.
Put your finger on 4. Now jump to the right three times: 4 → 5 → 6 → 7. You land on 7. So 4 + 3 = 7. Each jump added one, and three jumps added three.
Worked example 2: subtracting by jumping left
Work out 9 − 2 on the number line.
Put your finger on 9. Now jump to the left two times: 9 → 8 → 7. You land on 7. So 9 − 2 = 7. Jumping left made the number smaller, just as taking away should.
Worked example 3: finding the number in between
Which number sits exactly between 5 and 7?
Find 5 and 7 on the line. There is just one stone between them: 6. It is one step after 5 and one step before 7 — right in the middle. The number line makes "in between" easy to see, because you can point straight at it.
Worked example 4: how far apart?
How far is it from 3 to 8?
Start at 3 and count the jumps to 8: 3 → 4 → 5 → 6 → 7 → 8. That is 5 jumps. So 3 and 8 are 5 apart. Measuring the gap between numbers is another superpower of the number line, and it connects to taking away: 8 − 3 = 5.
Why the number line matters
The number line is a thinking tool you will use for years. Right now it helps you add and subtract small numbers. Later it grows to show bigger numbers, numbers between numbers, and one day even numbers below zero. Because it shows numbers in order and to scale, it gives you a strong mental picture of how numbers relate. Children who picture a number line in their heads find mental maths much easier. It also pairs beautifully with counting backwards and skip counting.
Try it yourself
- Make a floor line. Lay number cards 0 to 10 on the floor in a row. Stand on 4 and hop right 3 times. Where did you land? You just did 4 + 3!
- Jump back. Stand on 9 and hop left 2 times. Where are you? That is 9 − 2.
- In between. Point to 5, then 7. Which stone is in the middle? Try other pairs.
- Closer race. Pick a target like 10. Is 8 or 3 closer to it? Count the jumps to check.
Use your finger to travel the line every day, and soon you will picture it even with your eyes closed.
Quick quiz
Test yourself and earn XP
On a number line, which way do the numbers get bigger?
Numbers get bigger as you move to the right and smaller as you move to the left.
Start at 4 and jump 3 steps to the right. Where do you land?
4 + 3 = 7. Jumping right means adding, so 4 then 5, 6, 7.
Start at 9 and jump 2 steps to the left. Where do you land?
9 − 2 = 7. Jumping left means subtracting: 9 then 8, 7.
Which number sits exactly between 5 and 7?
6 sits one step after 5 and one step before 7, right in the middle.
On the line, which number is closer to 10: 8 or 3?
8 is only 2 steps from 10, while 3 is 7 steps away, so 8 is closer.
FAQ
A number line helps children see numbers in order, compare them, and add or subtract by jumping along the line. It turns counting into a clear picture.
Numbers grow as you move right, so adding (making more) moves you right. Subtracting (making fewer) moves you left, where numbers are smaller.
Children usually start using a simple 0–10 or 0–20 number line around ages 4 to 6, then move to larger lines as their counting grows.
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