What is a cube number?
Year 5 recognises cube numbers and the notation ³. Year 6 uses cubes to find the volume of a cube. Below: what it means, a worked example, the mistake to watch for and an 11+ question.
The answer
A cube number is what you get when you multiply a whole number by itself, and then by itself again.
What it means
2 × 2 × 2 = 8, so 8 is a cube number. It is written 2³, which is read "2 cubed".
They are called cube numbers because that many small cubes build a bigger cube: 8 small cubes make a 2 by 2 by 2 cube.
The cube numbers up to 10 × 10 × 10 are 1, 8, 27, 64, 125, 216, 343, 512, 729 and 1,000.
A worked example
Work out 4³
- The small 3 means three 4s multiplied together.
- 4 × 4 = 16, then 16 × 4 = 64. So 4³ = 64.
The common mistake
Reading 4³ as 4 × 3 = 12. The small 3 means 4 × 4 × 4, which is 64.
How it comes up in the 11+
Which number between 60 and 70 is both a square number and a cube number?
Answer: 64
- Square numbers between 60 and 70: only 64 (8 × 8).
- Cube numbers between 60 and 70: only 64 (4 × 4 × 4).
- 64 is on both lists.
Related words and practice
More maths words
Questions parents ask
Is 1 a cube number?
Yes. 1 × 1 × 1 = 1, so 1 is both the first square number and the first cube number.
What is 10 cubed?
10 × 10 × 10 = 1,000.
Knowing the words is half of an 11+ maths question
11+ papers use maths vocabulary without explaining it. The free diagnostic checks maths, English and both kinds of reasoning, and shows what to practise next. No card is required.