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%%  Example 01-02-1 
%%  Copyright (C) 2017 Herbert Voss
%% 
%% ==== 
% Show page(s) 1
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\documentclass[]{screxa}
\pagestyle{empty}
\setlength\textwidth{143.0346pt}
\setlength\parindent{0pt}
%StartShownPreambleCommands

%StopShownPreambleCommands
\begin{document}
\(\sum_{i=1}^{n}i=\frac{1}{2}n\cdot(n+1)\)\\[10pt]
$\sum_{i=1}^{n}i=\frac{1}{2}n\cdot(n+1)$\\[10pt]
\begin{math}
  \sum_{i=1}^{n}i=\frac{1}{2}n\cdot(n+1)
\end{math}
\end{document}
