If we're going to discus number theory, I think we should have a separate thread. Well, don't look at me! I do know the ancient Greeks were unable to develop algebra, since they reasoned "x² + x" is adding an area to a length, which is silly. Didn't bother the Babylonians, though: they invented the formula for solving quadratic equations by geometry.

Steve

P.S. If you want to know more, there's a site called "Ask Dr Math" somewhere, but you have to be still at school (or a liar!) to qualify.