Quant Concepts-Square of Numbers

Over the next few weeks , I will be covering some essential quantitative ability concepts which are a must for cracking the QA/DI section of CAT.

Let me start by explaining the concept of calculating squares of numbers.

Say , a number 312

312^2.

Determine the closest power of  100/10 as the case may be which is called the base.

In this case we obtain a base of 300.

represent 312^2 as (300+12)^2. here, deviation=12.

 Now,

 follow the step

ldigit(s) before 0 in base x  (number  + deviation) | deviation^2 where | is a separating  line separating 2 parts of calculation.

 

Remember ,

no. of digits on right side of the imaginary line should be exactly same as the no. of zeros in our base.

 

So, our problem boils down to:

3 x (312 + 12) | 12^2

3x324 | 144

972 | 144

= 97344....1 of 144 carried .

Another example:

38^2

base 30

3x(38 + 8 ) | 8x8

= 138 | 64

= 1444( as only digit should be on the right side of the imaginary line as base has one zero)

So,the 6 in the imaginary part is added to 138.

Comments are welcome and in case of doubts just leave a comment. I will cover them and other concepts in the next blog.

 

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