%% 
%%  Ein Beispiel der DANTE-Edition
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%%  2. Auflage
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%%  Beispiel 09-03-7 auf Seite 384.
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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{145.16928pt}
\setlength\parindent{0pt}
\setcounter{equation}{6}
\renewcommand\theequation{9.\arabic{equation}}
%StartShownPreambleCommands
\makeatletter
\renewcommand*\@eqnnum{{%
  \normalfont\normalcolor[\theequation]}}
\makeatother \newcommand*\diff{\mathop{}\!\mathrm{d}}
%StopShownPreambleCommands
\begin{document}
\begin{equation}
f(x)= \int\frac{\sin x}{x}\diff x
\end{equation}
\end{document}
