Meh. If you know the trick exists, you can derive it from first principles, which for some people (me included) is a much easier "trick" than accurately remembe

Meh. If you know the trick exists, you can derive it from first principles, which for some people (me included) is a much easier "trick" than accurately remembering the exact steps/process for something like this. Maybe there's a important semantic difference between derive and deduce? But I totally agree with the grandparent poster.