I know this is a total noob question, but once a number is so big power towers are useless, how do you tell how big a number is compared to other numbers? I know if they're in the same notation it's pretty easy, but if I've got 2^^^^4 and I want to compare it to something in, say, Hyper-E notation (just an example), how do I do that?

I'm also having trouble with the Fast-Growing Hierarchy. Say you've got . After you solve the first , you have and I just have no idea where to go from there.

I guess I'm not used to thinking beyond exponents. Can anyone help me improve?