Since this is in math puzzles I've hidden my solution
Spoiler:
I posted it in here not as a challenge to others but really as an answer to something I was just wondering. I was recently told to think of the largest possible number that still has some kind of meaning. I decided that the total number of atoms in the observable universe factorial is the largest number that still has any relevant meaning... I can't believe that even g1 is larger... considering graham's number is g64. Graham's number must really be the largest number that has any meaning.