Aptitude

How to find out Square root and Cube root of any number

Finding Square root and cube root was not so easy for no-mathematics background students.  Square root and cube root are the important basic things you need to know while solving aptitude problems.

There are many  traditional methods including Vedic Mathematics to solve them but these methods consumes a lot of time in exam and you all know we can’t waste our time in solving these basic things during solving exam paper.

So there are some self-implemented short tricks we are discussing here may be help you in these topics. So let’s begin–

Also Read – How to find out Square of Any Number with short trick.

#1. Square Root of any number:

Before finding the square root of any number you need to learn the following steps –

  • Step 1 – Find the nearest square to the given number.
  • Step 2 – Now divide the given number by that nearest square’s square root.
  • Step 3 – Add the denominator to the result of the step (2).
  • Step 4 – Now divide the resultant from step (4) by 2 always.
  • Step 5 – Hurray you got the result, the square root of that number.

Ex. 1.  √18 = ?  

 

Explanation of the above image –

  • Step 1 – 16 is the nearest square to the given number 18.
  • Step 2 – Square root of 16 = √16 = 4, So divide 18 by 4. i.e. 18/4 = 4.5
  • Step 3 – Now add the denominator to the resultant i.e. 4.5 so 4.5 + 4 = 8.5
  • Step 4 – Always divide the resultant by 2, i.e. 8.5/2 = 4.25 answer.

 Note: I suggest you to learn square of at least 1-50 numbers mentally (without paper pen)

#2. Finding Cube Root with easy Approach

Before starting I specially suggest you to learn cube of 1 -10 numbers. We are providing here cube table of 1-10 numbers –

NumberCube
11
28
327
464
5125
6216
7343
8512
9729
101000

You need to remember two basic rules-

  • If a number is ending with 2 ⇒ The Answer will ends with 8, And vice versa.
  • If a number is ending with 3 ⇒ The answer will ends 7. And vice versa.

Cube Root short trick
So let’s start with some steps –

Step 1 – Break the given number into pair of 3-3 from the right side. No matter if last pair (means first left pair) doesn’t have 3 digits. And Place slash (/) between the pairs.

Step 2 – Now see the last digit of the right side pair and write the last digit of our answer according to the above two rules.

Step 3 – Now move to second pair, from the table, find the number which cube is nearest and less than of the second pair. Write that digit, it will be the second last digit of our answer.

Note: This method is roundup method of finding cube root.
Let me know if you have any confusation.