[SoLiDUS]

From what I could gather, it is simply a modified number trick: neat, but
utterly useless biggrin:

It only works because the right-hand side creates an equality (thanks, capt.
Obvious!) provided one inputs the proper numbers, Z having a special trait.
What got me interested in your trick was the square root idea: I've always
wondered whether calculators used a special equation for solving the above
mentioned or used a brute force method...

I've checked a couple of sites and one method, the CORDIC Algorithm, can
solve the square root problem with a special equation. Check it out of you
want:

[url:3782a]http://www.math.utep.edu/Faculty/helmut/cordic/wcordic.html[/url:3782a]

I'll keep looking to see if they all use this method...