So I say this puzzle online a few days ago and found it quite interesting. The original question was
Make $120$ using only five $0$s.
Well, I said to myself, this is utterly trivial. Note that $$ 120 = 5! = (0! + 0! + 0! + 0! + 0!)!. $$ But what if we want to do it for an arbitrary number $n$ and an arbitrary number of $0$s, $m$. That is: we want to make $n$ using only $m$ zeroes. Clearly, using my solution above, we can make $n=m!$ using $m$ zeroes.
For $n=121$ and $m=5$, this is tougher and I can't seem to find a solution. Does anybody want to try to take on some general cases?