NUMBER

Cube Numbers

Learn the reliable method for cube numbers, then apply it to 11+ exam-style questions.

1 · WHAT YOU NEED TO KNOW

The idea

A cube number is made by multiplying an integer by itself three times.

Picture itFollow the number relationship
2 · THE METHOD

Follow these steps

  1. Identify the integer being cubed.
  2. Calculate n × n × n.
  3. Check the result against known cubes such as 1, 8, 27, 64 and 125.
3 · WORKED EXAMPLES

See the method in action

Example 1

Which value is equal to 7 cubed?

  1. 7³ means 7 × 7 × 7 = 343.
Answer: 343
Example 2

A cube has volume 729 cm³. Its edge length is increased by 1 cm. What is the new volume?

  1. Since 729 = 9³, the original edge is 9 cm.
  2. Increasing it gives 9 + 1 = 10 cm, and 10³ = 1000 cm³.
Answer: 1000 cm³
4 · ELEVENSPRINT TIP

A useful shortcut

Check the result against known cubes such as 1, 8, 27, 64 and 125.

5 · COMMON MISTAKES

Watch out for these

6 · TRY IT YOURSELF

Three fresh questions

Ready to check the method? You will get three fresh, validated questions.