%% 
%%  A DANTE-Edition example
%% 
%%  Beispiel 02-26-5 auf Seite 105.
%% 
%%  Copyright (C) 2010 H. 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.
%% 

%%Run also: >>  << 
% Show page(s) 1

\documentclass[]{article}
\pagestyle{empty}
\setlength\textwidth{194.59192pt}
\usepackage[utf8]{inputenc}

\usepackage[expproduct=\cdot]{siunitx}
\sisetup{tabparseonly}
\usepackage{booktabs}

\begin{document}
\begin{tabular}{ S S[tabnumalign=left]
  S[tabnumalign=right]}\toprule
\emph{Zentriert} & \emph{Linksbündig}
  & \emph{Rechtsbündig} \\\midrule
14.2    & 14.2    & 14.2 \\
1.23456 & 1.23456 & 1.23456\\
1.2e3   & 1.2e3   & 1.2e3\\\bottomrule
\end{tabular}
\end{document}