Circumference of a circle | Maths | Quizalize & Oak National Academy

Starter quiz

Which part of the circle is labelled?
- circumference
- diameter ✓
- radius
If a circle has a diameter of 12 cm then its radius will be ______ cm.
- '6' ✓
$\pi$ is the ratio between which two parts of a circle?
- the radius and diameter
- the radius and circumference
- the diameter and circumference ✓
Which two formulae can be used to calculate the circumference of a circle?
- $C = \pi d$ ✓
- $C = 2\pi d$
- $C = \pi r$
- $C = 2\pi r$ ✓
A circle with diameter 12 cm has a circumference of ______ cm.
- 6 $\pi$
- 12 $\pi$ ✓
- 24 $\pi$
A circle with radius 20 cm has a circumference of ______ cm.
- 10 $\pi$
- 20 $\pi$
- 40 $\pi$ ✓

Which part of the circle is labelled?
- 'circumference' ✓
A circle with a diameter of 6 cm has a circumference of ______ cm, when rounded to 1 decimal place.
- '18.8' ✓
The circumference of the circle is ______ cm, when rounded to 3 significant figures.
- '25.1' ✓
Which calculation would find the radius of a circle with circumference 20 cm?
- $20 \div$ $1 \over 2$ $\pi$
- $20 \div \pi$
- $20 \div 2\pi$ ✓
The circumference of a circle is 30 cm. The diameter of the circle is ______ cm, when rounded to 1 decimal place.
- '9.5' ✓
Starting with the smallest, sort the circles in ascending order of size.
- 1
  
  ⇔
  
  a circle with circumference 10 cm
- 2
  
  ⇔
  
  a circle with diameter 4 cm
- 3
  
  ⇔
  
  a circle with radius 3 cm

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The formula can be used to find the circumference when you know the diameter.
The formula can be used to find the circumference when you know the radius.
The formula can be used to find the radius or diameter when you know the circumference.
These answers will be rounded to an appropriate degree of accuracy.
For the answer to be exact it needs to be left in terms of π.

When writing answers in terms of π, pupils may think that π is the units.

π is a constant and makes up part of the numerical component of the answer. Units (such as square metres) still need to be stated.

Circumference - The circumference of a circle is the perimeter of the circle.
Radius - The radius of a circle is any line segment that joins the centre of a circle to its edge.
Diameter - The diameter of a circle is any line segment that starts and ends on the edge of the circle and passes through the centre.