Consider the series: SUM (when k=1 to k=infinity) of 1/(k^2). I know the series converges to some value S, but how can I find out what S is?
you asked for it ...
Fermat's Last Theorem: The Basel Problem
Here you have 14 proofs: http://secamlocal.ex.ac.uk/people/st.../etc/zeta2.pdf
Tonio