TITLE: Algorithm for computing square root of a perfect square integer?
QUESTION [9 upvotes]: My question is the following:

Is there a polytime non-numerical
  algorithm for computing square root of
  perfect square integers?

The more elementary the algorithm is, the better! 

EDIT: 
This is probably the most silly question I ever asked (I hope!). As pointed out by picakhu, since the input integer $n$ is perfect square, we can simply do a binary search to find the number whose square equals to $n$.

REPLY [10 votes]: The following should suffice, from Cohen: A course  in computational algebraic number theory.
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