Maths topic

number lines

A number line shows numbers in order with equal spaces, so we can locate values, compare numbers and show jumps.

Practise number lines Explore number lines Back to topics

the big idea

A number line is a straight line for numbers. The numbers stay in order, and the spaces between tick marks must be equal if the step is equal.

order left to right
spacing equal spaces
jumps +5 or -2 steps

move along a number line

Choose a number line and watch the marker and jumps explain the value.

+7 0 1 2 3 4 5 6 7 8 9 10 7

0 to 10

scaleeach space is 1 markermarker at 7 jumps7 is 7 one-step jumps from 0.
number line

numbers in order

A number line keeps numbers in order. Numbers usually get larger as you move to the right.

  • Numbers to the right are greater.
  • Numbers to the left are smaller.
  • Zero can sit in the middle when the line includes negative numbers.
-3 -2 -1 0 1 2 3 4 5 2
smaller larger to the right

equal spaces and scale

The scale tells us how much each equal space is worth.

  • A tick mark is one marked position on the line.
  • Equal spaces mean equal steps.
  • A line labelled 0, 5, 10, 15 has a scale of 5.
0 5 10 15 20 15

Equal spaces. Each step is worth 5.

locating numbers

To locate a number, read the labels and count the equal steps between them.

  • Start from a label you can see.
  • Count by the scale, not always by ones.
  • The marker sits on the tick mark for the number.
0 1 2 3 4 5 6 7 8 9 10 7

The marker is on 7.

jumps and sequences

Jumps on a number line can show adding, subtracting and skip counting.

  • Forward jumps can show addition.
  • Backward jumps can show subtraction.
  • Skip counting uses the same jump size each time.
+5 +5 +5 0 5 10 15 20 15

0, 5, 10, 15 shows three equal jumps of 5.

comparing on a number line

A number line helps us compare numbers by looking at their positions.

  • The number farther right is greater.
  • The number farther left is smaller.
  • This works for positive numbers, zero and negative numbers.
-5 -4 -3 -2 -1 0 1 2 3 4 5 3 -2

3 is greater because it is to the right of -2.

fractions, decimals and negatives

Number lines can show more than whole numbers. Fractions and decimals sit between whole numbers. Negative numbers sit to the left of zero.

  • Negative numbers are less than zero.
  • 1/2 is halfway between 0 and 1.
  • 0.5 is the decimal for one half.
negative
-5 -4 -3 -2 -1 0 1 2 3 4 5 -2
fraction
0 1/4 1/2 3/4 1 3/4
decimal
0 1/4 1/2 3/4 1 0.5

number line words

These words help us read, build and explain number lines.

1 number line line

a straight line that shows numbers in order

2 tick mark mark

one marked position on the line

3 interval space

the space between two tick marks

4 scale step size

what each equal space is worth

5 jump move

a step forward or backward on the line

6 negative < 0

a number less than zero

7 fraction/decimal between

numbers that can sit between whole numbers

number line facts

numbers get larger move right
numbers get smaller move left
equal spaces equal steps
0, 5, 10, 15 scale of 5
jumps forward addition
1/2 and 0.5 halfway between 0 and 1

real world examples

thermometer reading temperatures below and above zero
ruler measuring length along a line
maps using a scale to show distance
timelines placing events in order
sport tracking gains and losses on a field
money showing increases and decreases

quick number lines quiz

Try a few number line ideas. This quiz only asks about ideas shown on this page.

Which direction do numbers usually get larger on a number line?

What must be equal when the scale is equal?

On a line labelled 0, 5, 10, 15, what is the scale?

Which number is greater: -2 or 3?

Which value is halfway between 0 and 1?