First that doesn't seem to be an issue but rather a question:-)
Then, the descriotion says:

We approximate the square root of a number n by taking an initial guess x, an error e and repeatedly calculating a new approximate value x using: (x + n / x) / 2; we are finished when the previous x and the new x have an absolute difference less than e.

So the method is clearly given, not to prevent creativity, but to be in order to compare the results... The answer to your question is not since doing so you won't be able to pass the tests, sorry!