CareerCup

Newton Raphson method.

public static double Sqroot(double x)
        {
            double fa = x / 2;
            double sa = x / fa;
            double ta = (fa + sa) / 2.0;
            while (Math.Abs(x - Math.Pow(ta, 2)) > 0.000000001)
            {
                fa = ta;
                sa = x / fa;
                ta = (fa + sa) / 2;
            }
            return ta;
        }

use Newton raphson method to get upto desired precision value

You could do a binary search for the square root. This is the most elementary approach that requires you to know the least math. It's also arguably a very comp-sciency way of doing it.

If we had to just return the |sqr_root(n)| to zero decimal places,
1) make a large array such that A[i]=i^2;
2) bin search this array for the input number(x) or the number just less than x(say y);
3) return index of x or y as per case.

Did they really expect someone to know NR for telephonic?? :O

@eugene.yarovoi, Can you please explain your solution a little.

> Do a binary search

Of what?