# custom chapter numbering with decimals

I would like to start a report with the Chapter 3.6 (and consecutive) until 3.9. I have been looking for these types of commands, but they are not working as I want.

• Welcome to TeX.SX! Your chapters should start with 3.6.. What is 3.6 then? A section? – user31729 May 13 '15 at 16:34
• Oh God! Silly me! Yes, I meant, Section 3.6! – cgo May 13 '15 at 16:37

\renewcomand\thechapter{3.\arabic{chapter}}
\setcounter{chapter}{5}


in the preamble should make the first \chapter 3.6

Principally it's possible to set the counters of chapter andsection accordingly, but it will look a little bit strange.

Since the section counter is reset each time the chapter counter is increased, the setting of section counter must be done after \chapter is called.

\documentclass{report}

\usepackage{blindtext}

\setcounter{chapter}{2}

\begin{document}
\tableofcontents

\chapter{My real first chapter}
\setcounter{section}{5}

\section{A section}

\blindtext[5]

\section{A} % Will be 3.7
\section{B} % 3.8
\section{c} % 3.9

\chapter{Second chapter}  % Sections are set to 1, chapter is 4 now
\section{Start over with 1}

\end{document}


# Class with chapters

If the class contains chapters and the "3" in "3.6" means the chapter number:

\documentclass{report}

\setcounter{chapter}{3}
\setcounter{section}{5}

\begin{document}
\tableofcontents
\section{First section}
\subsection{First subsection}
\subsubsection{First subsubsection}
\section{Second section}
\section{Third section}
\section{Forth section}
\end{document}


# Class without chapters

If the class does not contain chapters such as article, then the appearance of the section counter can be prefixed with 3.. The longer section number also requires more place in the table of contents, see the following example:

\documentclass{article}

\usepackage{etoolbox}

\pretocmd\thesection{3.}{}{%
\errmessage{Patching \noexpand\thesection failed}%
}
\setcounter{section}{5}

% Extra place is needed for the section number in the table of contents
\makeatletter
\patchcmd\l@section{1.5em}{2.3em}{}{%
\errmessage{Patching \noexpand\l@section failed}%
}
\makeatother

\begin{document}
\tableofcontents
\section{First section}
\subsection{First subsection}
\subsubsection{First subsubsection}
\section{Second section}
\section{Third section}
\section{Forth section}
\end{document}
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