3↑↑↑3= (or near) in power tower of 10 or in ( Knuth ) arrow ↑ notation of 10 to get a sense of it's order of magnitude; I grasp numbers more easily with 10
3↑↑↑3 being the first really huge number in the awesome crescendo of Graham's number, I suspect that it is still within the grasp of imagination, but it would help to get it in terms of 10 instead of 3.
I can't find it on the web, I am pretty sure I'm not the only one to wonder about this....
Please note that I am really talking about the small (?!) 3↑↑↑3 (Sun Tower), not G1=3↑↑↑↑3