[beeworker]

It's really easy to memorize if your teacher presents it to the tune of pop goes the weasel... Whether it's worthwhile to memorize or not, use a computer or not, the valuable conceptual struggle teachers need to focus in on is in what the answer means, and when to apply it, not in deriving the formula, though that can be a useful struggle if you doubt the power of proof or the rules of algebraic manipulation.