\documentclass[12pt]{article}
\begin{document}

Mathematics can be displayed inline, for example $\int_0^1 x^2 dx$ or $\lim_{n\to\infty} \frac{1}{n}=0$, or can be displayed more prominently on a line by itself:
\[\lim_{n\to\infty} \frac{1}{n^2}=0\]
Then the ``normal'' text continues.
 

$\sqrt{2}$

$\sqrt[3]{2}$

$f(x)=\arctan{x}$

$f(x)=arctan(x)$

$\sin x, \ln x^2$
\[\sin(x)\]


I     have a computer.
Me too.\bigskip

Also I.

\$
10.55

\begin{eqnarray}
f(x)&=&\sin^2 (x)\\
g(x)&=& \cos 2x
\end{eqnarray}

\begin{center}
This text is centered.
\end{center}

$x_{2k}$

\textbf{Other} \textit{stuff} we can do.

\[
\left\{
\begin{array}{rrr}
2&-3&\arctan 4\\
5&6&7\\
\end{array}
\right\}
\]

\begin{enumerate}
\item Eins.
\item Dos.
	\begin{itemize}
	\item Eins.
	\item Dos.
	\end{itemize}
	\item Three.
\end{enumerate}\bigskip

\begin{itemize}
\item Eins.
\item Dos.
\end{itemize}




\end{document}