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Cube of a number is its multiplication by itself three times and the cube root is just the inverse of it. The cube root of a number is the opposite function of its cube. For example, if the cube of any number is a3 then its cube root will be a.
The cube root is a widely used concept in Mathematics, especially in geometry, where volumes of various shapes have cubic units.
Also Read: Cube and Cube Roots
| Table of Content |
Key Terms: Cube, Cube Root, Integer, Geometry, Prime Factorisation, Square Root
What is Cube Root?
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The cube root of a number a is a number that when multiplied thrice by itself gives the same number a.
- It is simply the inverse operation of a cube.
- The cube root of a number is just the opposite of cubing of that number.
- The cube root is denoted by the symbol ∛ which is just the “radical” symbol, which is used for the square root, with a little 3 over it.
For a perfect cube x of any integer y i.e., x = y3, then y is called the cube root of x and it is denoted by y = ∛x.

Cube Root
Cube Root of Non-perfect Cubes
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It is easier to find the cube root of numbers which are perfect cubes but for non-perfect cubes, we use the prime factorisation method. The steps to find the cube root of a non-perfect cube, 30, are as follows.
- Since we know 30 lies between 27 which is a cube of 27 and 64 the cube of 4. So, let’s consider the lower number here, i.e. 3.
- Dividing 30 by the square of 3: 30/9 = 3.33
- Subtracting 3 from 3.33 and then dividing it by 3.
- 3.33 - 3 = 0.33 & 0.33/3 = 0.11
- The final step is to add the lower number which we got in the first step and the decimal number obtained.
- 3 + 0.11 = 3.11
Therefore, the cube root of 30 is ∛30 = 3.11
Also Read: Decimal to Fraction Formula
Cube Root of 1 to 30
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The cube root of 1 to 30 is used very commonly and for that purpose, a table is given below.
| Number | Cube Root (∛) |
|---|---|
| 1 | 1.000 |
| 2 | 1.260 |
| 3 | 1.442 |
| 4 | 1.587 |
| 5 | 1.710 |
| 6 | 1.817 |
| 7 | 1.913 |
| 8 | 2.000 |
| 9 | 2.080 |
| 10 | 2.154 |
| 11 | 2.224 |
| 12 | 2.289 |
| 13 | 2.351 |
| 14 | 2.410 |
| 15 | 2.466 |
| 16 | 2.520 |
| 17 | 2.571 |
| 18 | 2.621 |
| 19 | 2.668 |
| 20 | 2.714 |
| 21 | 2.759 |
| 22 | 2.802 |
| 23 | 2.844 |
| 24 | 2.884 |
| 25 | 2.924 |
| 26 | 2.962 |
| 27 | 3.000 |
| 28 | 3.037 |
| 29 | 3.072 |
| 30 | 3.107 |
Also Read: Number System
Solved Examples
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To understand better the concept of the cube root a few examples are given below.
Example 1: Solve ∛30 – 3.
Solution: Here, we have
∛30 = 3.1072
Thus,
∛30 – 3 = 3.1072 – 3 = 0.1072
Example 2: Solve ∛5 + ∛8.
Solution: Taking the value of ∛5 and ∛8 from the table given above
∛5 = 1.70997.. = 1.71
∛8 = 2
Thus,
∛5 + ∛8 = 1.71+2 = 3.71
Also Read:
| Related Topics | ||
|---|---|---|
| Square Root Formula | Exponent | Sum of Squares |
| Prime Numbers | Closure Property | Powers and Negative Exponents |
Things to Remember
- The cube root of a number is the opposite of its cube function.
- Cube root of non-perfect numbers is found through the prime factorization method.
- The cube root of unity is unity.
- The symbol of cube root is ∛.
- Cube root of perfect cubes are integers but of non-perfect cubes, it will be a decimal.
Sample Questions
Ques: Evaluate the value of 5∛9. [2 marks]
Ans: Fromm table we know,
∛9 = 2.080
Therefore,
5∛9 = 5 x 2.080
= 10.4
Ques: Solve 6∛12. [2 marks]
Ans: From the table, the value of ∛12 is 2.289
Thus, 6∛12 = 6 x 2.289 = .13734
Ques: Evaluate the value of 2∛14. [2 marks]
Ans: From the table, the value of ∛14 is 2.410
Thus, 2∛14 = 2 x 2.410 = 4.820
Ques: What is the value of three times the cube root of 20? [2 marks]
Ans: First using the table let’s find out the value of ∛20
∛20 = 2.714
Now, three times 2.714 = 3 x 2.714 = 8.142
Ques: What should be added to the cube root of 6 so that the result is 9? [2 marks]
Ans: The cube root of 6 is 1.817
Now, the number to be added = 9 - 1.817 = .7183
Ques: Solve 12∛25. [2 marks]
Ans: ∛25 = 2.924 (from the table)
Thus, 12∛25 = 12 x 2.924 = 35.088
Ques: Evaluate the value of 10∛10. [2 marks]
Ans: From table the value of ∛10 is 2.154
Now, 10∛10 = 10 x 2.154 = 21.54
Ques: Solve 30∛30. [2 marks]
Ans: From the table, the value of ∛30 is 3.107
Now, 30∛30 = 30 x 3.107 = 93.210
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