Cube roots
for 8th grade

Calculating cube roots

To calculate the cube root of a number, we need to find a number which when multiplied by itself twice (i.e., raised to the power three) gives the original number. The cube root of a number is denoted by the symbol ³√.

For example: 3 x 3 x 3 = 27 so ³√27 = 3

To calculate the cube root of a number using a calculator, we can simply enter the number and press the cube root button (³√). For example, to calculate the cube root of 64, we can enter 64 and then press the cube root button to get the answer 4. We know the answer is correct because 4 x 4 x 4 = 64. Here are some more examples:

Cube root of 8: ³√8 = 2

Cube root of 125: ³√125 = 5

Cube root of 216: ³√216 = 6

Cube root of 343: ³√343 = 7

Cube root of 512: ³√512 = 8

Cube root of 729: ³√729 = 9

Cube root of 1000: ³√1000 = 10

Most numbers do not have cube roots that are integers. Sometimes we need to find the nearest integer to the cube root of a number. For example, the cube root of 67 is approximately 4.06, so the nearest integer to the cube root of 67 is 4. Here are some more examples:

³√50 = ~3.68 which is 4 to the nearest integer

³√120 = ~4.93 which is 5 to the nearest integer

³√500 = ~7.94 which is 8 to the nearest integer

In this topic you are asked to calculate the cube root or the nearest integer to the cube root for numbers up to 1000. You will probably need a calculator when answering questions in this topic.

Related topics

• Identify square numbers
• Calculate square roots