How to calculate a cube number. (examples include 2 cubed and 4 cubed).

A cube number is found by multiplying a number by itself 3 times. A tiny 3 on the top right of a number means you have to cube the number.

Example 1

Work out the cube of 2 (which can be written as 2³).

To work this out, all you need to do is multiply the number by itself 3 times:

That is:

2 × 2 × 2 = 8.

So 8 would be a cube number.

Example 2

What is 7 cubed?

Again all you need to do is multiply the number by itself 3 times.

That is:

7 × 7 × 7 = 343

So 343 is also a cube number.

Example 3

Work out 4³.

Like before, all you need to do is work out 4 × 4 × 4 = 64.

So 64 is also a cube number.

Example 4

Work out the cube of -5.

To work this out all you need to do is multiply the number by itself 3 times:

So -5 × -5 × -5 = -125

(Since -5 × - 5 = 25 and 25 × -5 = 125).

Example 5

Work out the cube of 1/2.

Just like the previous examples, all you need to do is work out:

½ × ½ × ½

Just multiply all the numerators and denominators together to give an answer of 1/8.

It is a good idea to remember your first 10 numbers which are:

1³ = 1

2³ = 8

3³ = 27

4³ = 64

5³ = 125

6³ = 216

7³ = 343

8³ = 512

9³ = 729

10³ = 1000

Remembering these cube numbers will help finding cube roots much easier to calculate.

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