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%%  Ein Beispiel der DANTE-Edition
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%%  2. Auflage
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%%  Beispiel 06-03-106 auf Seite 279.
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%%  Copyright (C) 2016 Herbert Voss
%% 
%%  It may be distributed and/or modified under the conditions
%%  of the LaTeX Project Public License, either version 1.3
%%  of this license or (at your option) any later version.
%% 
%%  See http://www.latex-project.org/lppl.txt for details.
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% Show page(s) 1
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\documentclass[]{exaarticle}
\pagestyle{empty}
\setlength\textwidth{121.16928pt}
\usepackage[utf8]{inputenc}
%StartShownPreambleCommands
\usepackage[exponent-product=\cdot]{siunitx}
\usepackage{booktabs}
\sisetup{table-format=1.3e2,table-number-alignment=center}
%StopShownPreambleCommands
\begin{document}
\begin{tabular}{SS[table-align-exponent=false]}\toprule
\emph{Spalte} & \emph{Spalte} \\\midrule
1.2e3         & 1.2e3\\
1.234e56      & 1.234e56\\\bottomrule
\end{tabular}
\end{document}