\documentclass[]{article}
\usepackage{amsmath}
\title{Hello World in \LaTeX}
\date{}
\begin{document}
\maketitle
\section*{Ramnujan expression for $\pi$}
Since this a \LaTeXe document we can do some funny things like expressing the Srinivasa Ramanujan expansion for $\pi$
\[
\frac{1}{\pi} = \frac{2\sqrt{2}}{9801} \sum^\infty_{k=0} \frac{(4k)!(1103+26390k)}{(k!)^4 396^{4k}}
\]
\end{document}
