Math is cool

Not sure how this came up, but this is what happens when two physicists email each other. I love stuff like this (minor edits for clarity):

Does 0.99999....(i.e. forever 9s) equal 1? Actually, yes:

Proof:
(1) x = .999999....
(2) 10x = 9.99999....
(3) Subtract (1) from (2)
(4) 9x = 9
(5) x = 1

I think the inherent neatness of equations underlies systems biology. Because everything is a system. And no, I don't know what systems biology actually means.