Square root of a number within seconds

How to know square root of number within seconds.

Hi folks, this time we are going to learn something very important from quantitative and data interpretation point of view.

We can add, multiply, divide, subtract but when it comes to square root we try to ignore it or make illogical guess like its close to that etc etc.

Lets try to find out square root of 19.

19 lies between 16 and 25, so the square root of 19 will be 4 point something.

Now divide 19 by 4 (as 16 is closer to 19) to get 4.75.

Or alternatively do 19-16=3 so divide ¾ to get 0.75 and append it to 4.

And take average of 4.75 and 4 to get the result as 4.375. While the square root by calculator is 4.359

Now, lets try to find out square root of 593472, wow thats a big number!

So, first analyze 7²=49, so 700²=49,00,00 [append double number of zeros]

8²=64 so 800²=64,00,00

So answer lies between 700 and 800.

Now, divide 593472 by 800 [as 640000 seems closer to 593472 than 490000] , to do this assume number be 5934 [ i.e. strip number as number of zeros of your divisor, here it is 2] and divide it by 8.

We get 741, now take the average of 741 and 800 to get 770.50, while actual square root is 770.37 pretty close isn't it?

Now try to find out square root of these (Select Between <<>> to see the answer) :

78=<<8.83>>

176=<<13.26>>

331=<<18.19>>

9873=<<99.36>>

493485=<<702.48>>

There might not be a direct question asked in CAT/XAT/GMAT/GRE/SAT etc but this trick
comes handy in application of data interpretation questions and quantitative ability.

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Thats it folks, catch you next time, until then if you have any query regarding anything
contact me at friggere.Sumit@gmail.com