# Section and chapter numbering

My first chapter should not have a number next to it (not in the TOC nor in the chapter itself). The other chapters however should have a number. I can do this by using \chapter*{...} However, this will also remove the chapter number from the sections inside that chapter. The toc will look like this then:

My first chapter

.1 My first section

While it should look like this:

My first chapter

I.1 My first section

How can I do this? Note that this only applies to my first chapter.

• Where does the I come from. Is it the Roman number I from the first chapter? Should the second chapter be numbered II? Can you please add a MWE to show us essential information like the class. – Schweinebacke Feb 6 '17 at 7:50

I think this will look strange, but yes it is possible. The reason for the missing chapter number is that you use Roman numbering for the chapters, and if you don't number it the chapter is number 0. The number 0 does not exist in roman numbering (which by the way is a big drawback of the numbering system). To get the number you need to increment the chapter counter. Something like this:

\documentclass{book}
\renewcommand\thechapter{\Roman{chapter}}
\begin{document}
\tableofcontents

\chapter*{First un-numbered}
\stepcounter{chapter}
\section{Section with strange numbering}
\section{Another section}

\chapter{First numbered}
\section{Section with numbering}
\section{Another section}

\chapter{Second numbered}
\section{A section}
\section{Another section}

\end{document}


But then the number in the section refers to a chapter number that does not exist. In this case I think it is better to completely remove the chapter numbering from the section numbers in the first chapter.

\documentclass{book}
\renewcommand\thechapter{\Roman{chapter}}
\begin{document}
\tableofcontents

\chapter*{First un-numbered}
\renewcommand\thesection{\arabic{section}}
\section{Section with strange numbering}
\section{Another section}

\chapter{First numbered}
\renewcommand\thesection{\thechapter.\arabic{section}}
\section{Section with numbering}
\section{Another section}

\chapter{Second numbered}
\section{A section}
\section{Another section}

\end{document}


Of course, it would be even better to have also the first chapter numbered.

\documentclass{book}
\renewcommand\thechapter{\Roman{chapter}}
\begin{document}
\tableofcontents

\chapter{First un-numbered}
\section{Section with strange numbering}
\section{Another section}

\chapter{First numbered}
\section{Section with numbering}
\section{Another section}

\chapter{Second numbered}
\section{A section}
\section{Another section}

\end{document}


• If you use \refstepcounter instead of \stepcounter you could even label the not numbered chapter. – Schweinebacke Feb 6 '17 at 8:48
• @Schweinebacke Yes, but it might be a bit confusing for the reader to have a reference to a non-existing chapter number:-) – StefanH Feb 6 '17 at 9:06
• More confusing than having section numbers with a chapter number prefix that does not have a corresponding numbered chapter? – Schweinebacke Feb 6 '17 at 9:12
• @Schweinebacke I would say about the same level of confusion – StefanH Feb 6 '17 at 9:18
• So it would result in confusion consistency. ;-) – Schweinebacke Feb 6 '17 at 9:23

As an addendum to the second example of SefanH's answer: Using scrbook instead of book and \frontmatter for the the part with the not numbered chapter already makes section numbers without chapter number prefix:

\documentclass{scrbook}
\renewcommand\thechapter{\Roman{chapter}}
\begin{document}
\frontmatter
\tableofcontents

\chapter{First un-numbered}
\section{Section with strange numbering}
\section{Another section}

\mainmatter
\chapter{First numbered}
\section{Section with numbering}
\section{Another section}

\chapter{Second numbered}
\section{A section}
\section{Another section}

\end{document}