square root upto infinity-substraction-shortcut trick for very typical questions of quantitative aptitude

dear readers, here I am telling you the shortcut trick of the square root upto infinity problem- substraction- which is asked in most competitive exams like cat, afcat, mat, gate, ssc, ibps etc.

Before learning to solve this question, you should know about the addition version of this question type. I have discussed that in my recent post. Please read that post first before reading this post  by clicking here.
So friends, here we are given a question in which we have to calculate the square root of 12 with simultaneously decreasing it with square root of 12 successively.
What we normally do is calculating the value of square root of 12 and then adding it successively until we reach a near value. But that process takes a lot of time.

So here I am telling you about a trick through which you can easily do this question in just 2 seconds.
I am explaining the solution of this problem here.
Assume 12 as x, remember x should be given even for this trick to work. If x is given odd, then the formula of the trick will change.
Now think of two consecutive factors of 12. i.e.
The value of n will be the answer of this type of problem.
The shorter value means 3 will be the answer.
Note: in addition (+)version of this type of problems, the bigger factor means n+1 will be the answer while in subtraction  version of this problem, n will be the answer.