Faster square roots?

Did you know if you multiply your
product by pi, and then use that as
the area of a circle while solving for
the radius, the result will be an
approximation of the square root
of your product.

Example:

let p (the product) = 492181
then √p = 701.5561274766261

492181*pi = 1,546,232~
(leaving off the fraction for
the sake of brevity)

area = 1,546,232

then the radius of the 'circle' would be 701.56

I wonder if anyone has stumbled on this before?