Cube Root 1 to 30: Steps to Calculate with Examples

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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

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


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:


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

Also Read:

CBSE X Related Questions

  • 1.
    The value of p for which roots of the quadratic equation $x^2 - px + 6 = 0$ are rational, is

      • $1$
      • $-5$
      • $25$
      • $\sqrt{5}$

    • 2.
      Two water taps together can fill a tank in $8\frac{8}{9}$ hours. The tap of larger diameter takes 4 hours less than the smaller one to fill the tank separately. Find the time in which each tap can separately fill the tank.


        • 3.
          A bag contains 25 balls. Some of them are yellow and others are green. One ball is drawn at random. If probability of getting a green ball is $3/5$, then find the number of yellow balls.


            • 4.
              A chord of a circle, of radius 14 cm, subtends an angle of $60^\circ$ at the centre. Find the area of the smaller sector and perimeter of the smaller segment.


                • 5.
                  Prove that $14 - 2\sqrt{3}$ is an irrational number, given that $\sqrt{3}$ is irrational.


                    • 6.
                      The dimensions of a window are $156\text{ cm} \times 216\text{ cm}$. Arjun wants to put grill on the window creating complete squares of maximum size. Determine the side length of the square and hence find the number of squares formed.

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