Add more content to explain basics of finding square roots

Having "passed" both the square root and cube root portions, i still have zero knowledge, much less understanding, of how to go about it. I used trial & error - guesswork. The video about cube roots says nothing at all about how to solve cube roots, he just solves them in two examples and points to factoring in a third. Factoring, btw, doesn't seem to help solve roots either, it can be helpful if things happen to factor evenly, otherwise you're back to guessing. I don't see how these sections possibly passed muster.

What's the cube root of 683? I have no idea. I have no idea where to being, but at least i've "passed" so i guess that's something.