Notation for equations doesn't work on stackoverflow.com, like it does on https://math.stackexchange.com/. As I can see both sites are use the same engine (both are part of the stackexchage), so why I couldn't write something like $\frac{4}{3}\pi r^3$
as in this question?
I'm aware about this solution, but I can't see any reason to use 3rd-party solution when there's a ready one on stackexchage.com.