Hi,

With this series of articles I would like to discuss a few fundas related to numbers / math that I have picked up over the years. We all have encountered questions in which if we knew the squares, we would have saved a few precious seconds. I always felt that if I was just a little bit faster, I might have done one more question in the exam. I am not saying that the fundas below would improve you drastically but I am sure you would find them a step in the right direction. I will start off with a simple funda.

How to calculate square of a number close to 50

This technique will work only for numbers which lie in the range [41,59] both ends included.

Funda - If the distance of the number from 50 is ‘x’, the last two digits will be x^2 and the first two digits will be 25+x. Let us check it out with an example.

#Suppose we want to calculate 54^2. The distance from 50 is 4.

ð  The first two digits would be 25+4 = 29

ð  The last two digits would be 4^2 = 16

ð  The square of 54 would be 2916.

#Suppose we want to calculate 43^2. The distance from 50 is (-7).

ð  The first two digits would be 25 + (-7) = 18

ð  The last two digits would be (-7)^2 = 49

ð  The square of 43 is 1849.

Now I guess you should be able to calculate the squares of numbers close to 50. I recommend that you practice it in your head without using a pen or paper.

How to calculate square of a number ending in 5

This technique will work for all numbers which end in 5. This will not work for numbers which end in other digits.

Funda – If we remove the last digit ‘5’ from our number and are left with x, then the square will be [Product of x and x+1]25.

#Suppose we want to calculate 65^2.

ð  We remove 5 from our number, we are left with 6.

ð  Product of 6 and 7 is 42

ð  The square of 65 is 4225

#Suppose we want to calculate 195^2

ð  We remove 5 from our number, we are left with 19

ð  Product of 19 and 20 is 380

ð  The square of 195 is 38025

I very strongly believe that just knowing more and more fundas is not going to help until and unless you practice them. So work on these ideas.

This post was published originally on FreshersWorld.