Wednesday, 3 May 2017

How To Find Cube Root Of A Perfect Cube In IBPS PO Exam

how to find cube root

Since we now know how to find the cube of a number using the cube formula, let us discuss how to find the cube root of a perfect cube. Understanding how to find square root of a number will help us understand how to find a cube root easily. We can apply the same method to find the cube root of any perfect cube. But here’s the best part -- Finding cube root of a perfect cube is simpler than finding square root of a number.

Generally speaking, in the simplification section of the question paper of any competitive exam or IBPS PO exam, we are given to find cube roots of only perfect cubes. But if we are required to find the cube root of a number as part of a question from the approximation section, then it may or may not be a perfect cube.

How To Find Cube Root Of A Number In Two Easy Steps

Firstly, you must memorise the cubes of numbers from 1 to 15.
how to find cube root
We have already learnt that there is a certain pattern seen when it comes to cubes of numbers:
how to find cube root
SMART METHOD
How to find cube root of a perfect cube in a smart method is a 2-step process

Example 1: Find ∛551368
Solution:
Step1: Decide the unit’s place of the result.
551368 ends with 8 = Cube root will end with 2
_2

Step2: Leave the last 3 digits and find the immediate perfect cube before the remaining number.
The immediate perfect cube before 551 is 512 = 83
That is the number in our ten’s place
82

551368 = 82

Example 2: Find ∛50653
Solution:
Step1: Decide the unit’s place of the result.
50653 ends with 3 = Cube root will end with 7
_7

Step2: Leave the last 3 digits and find the immediate perfect cube before the remaining number.
The immediate perfect cube before 50 is 27 = 33
That is the number in our ten’s place
37

50653 = 37

If you have the cubes of numbers from 1 till 15 memorised, finding the cube root of any perfect cube should be a matter of seconds. The few extra minutes saved in the exam can go a long way in helping you secure your dream job!

Remember that knowing a technique is quite ineffective when it comes to applying them in the exam. To perfect these techniques and smart methods of finding cube root of a perfect cube, you must give it enough practice.

how to find cube root
See our expert faculty, Rohit Agarwal explain how to find cube root of a perfect cube in the video below.


Let us put your practice to test:

Question 1: Find ∛148877
Question 2: Find ∛46656

Please write your answers in the comments below and tell us how long it took you to find the right answers.

Hot Tip: If it takes you anything more than 3 seconds, you need more practice to perfect this smart method of how to find cube root of a perfect cube.
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