Why

One reason people love mathematics is the way it gives insight in to things. Here is one celebrated result of what sum(1/k^2,k=1..infinity) is. It all depends on knowing sin(x)/x. The limit(sin(x)/x,x=0) =1 but for each integral multiple of Pi it is 0. Thus we have . This is also called as basel problem and it was genius of Euler who came up with this neat solution.