* Schroeppel, Richard <rschroe@sandia.gov> [Nov 15. 2017 07:40]:
Two more "never" examples from my youth ...
"What's the largest number expressible with three digits?" I think this was meant to be without additional arithmetic signs, since 999!!!!... is unbounded with an arbitrary number of !s. It was probably intended as a trick puzzle, with the wrong answer being 999. The answer given is 9^(9^9), which has around 300M digits, and can be written sign-free with superscripts. At the time, this was too big to compute as a decimal digit string. [Using 1s, 2s, or 3s, and four or more digits makes a more interesting puzzle.]
I computed 9^9^9 in 1999 just for the kick of it. I seem to recall someone somewhere said that this would never be possible, but have never been able to find (again) that text until now. Any pointers are welcome. Best regards, jj P.S.: with today's computers the computation takes around one minute on a single core.
[...]
Rich
[...]