Discussion
Why \sum_{n=1}^{\infty} 1/n^2 = \pi^2/6 keeps getting new proofs
The Basel problem has at least fourteen genuinely different proofs. What makes it such a magnet?
Inline maths like a_i, b_j and x_1 \cdot x_2 must survive markdown intact — underscores are not emphasis here.
Discussion 4
Plain reply, no maths at all — most comments look like this.
Replies nest. Inline maths works here too: the partial sums \sum_{n=1}^{N} 1/n^2 approach \pi^2/6 from below, which is why the numerical check further down is one-sided.
And a comment can ask the server for a number rather than assert one. The output below is what actually ran:
A separate top-level reply, to show the tree rather than one straight line.