Sum of infinite series - 1/n^2

[praharmitra]

How do you go about finding the sum, $$\sum \frac{1}{n^2}$$.

I remember studying it earlier, but don't quite remember how it was done..just tell me the method. i'll figure the rest out.

 

[dirk_mec1]

http://www.math.uu.se/~bjorklund/euler.pdf