For the final answer, I guess Big Omega, unless you don't count infinities in which case my answer is getting up and arguing with the professor because "the number of times I can recursively write TREE(TREE(TREE... is just as arbitrary as declaring a biggest theoretical number and assigning it a new symbol.
In fact the answer was a series of definitions of new biggest numbers, and you only defined one, instead of defining it, using it for its value of trees, then using that new term for more trees.
Man, I remember getting the kindergarten question at a point where my older brother had already told me that you can just add more digits and it always gets bigger.
I was so angry at that question, because what the hell do you want me to do here? I think, I ended up just cramming as many 9s into the box as I could, but that question is almost philosophical.
Clearly, I'm able to think of an even larger number by cramming one more 9 into there. So, what I've written down is always wrong. It is never the largest number that I'm actually able to think of. I'm telling you, I got forced into this life of lies and crime at a young age.
Only if it's "10 more" in the sense that anything bigger than that is also accepted. If you need to hit 57, because the average is 47, then yeah, good luck.