/sci/ - Science & Math

Alright, /sci/.
I want to know which one of you can think of the biggest number. Whoever has the biggest will receive a 30% off coupon for a smug sense of superiority. The rules are as follows:
1: Your number must be finite and real.
2: Your number must be computable and well defined. Even if you're using notation or part of a definition that was already posted in this thread, you must define it again in your post.
3: Your number must be defined in one post only (no two-parters).
4: The definition of your number must not involve any posts to come after yours.

I'll start with 0.