# Numbering theorems from 1 in each section

Is it possible to number every theorem from 1 in each section?

For example, I would like to have the first theorem in the nth section simply called Theorem 1 for every n.

• You should provide more information, but for a basic setup see my (possible) answer – user31729 Jan 18 '15 at 6:26
• @ChristianHupfer: Thanks so much, that is close. I think I have no more information to provide with :) Thanks to your answer, what I want is to make Theorem 1.1 and Theorem 2.1 both as simply Theorem 1. – Megadeth Jan 18 '15 at 6:29
• I've updated my solution – user31729 Jan 18 '15 at 6:38

The newtheorem command has an optional third argument, which is designed for specification of the counter which drives the resetting of the theorem counter, in this case section, since the request is to start over the theorem number with 1 in a new section.

In order to suppress the leading 1. etc. from the theorem label, the easiest way is the redefine \thetheorem command which is responsible for printing the theorem label number.

\documentclass{article}

\usepackage{amsthm}

\newtheorem{theorem}{Theorem}[section]

\renewcommand{\thetheorem}{\arabic{theorem}}

\begin{document}

\section{First}

\begin{theorem}{Theory on Brontosaurs, by Miss Ann Elk}

Brontosaurs are thin at one end, thick in the middle and thin again at the other end.
\end{theorem}

\begin{theorem}{First of second}
Blabla
\end{theorem}

\section{Second Section}

\begin{theorem}{First in 2nd section}
Blabla
\end{theorem}

\begin{theorem}{First of second}
Blabla
\end{theorem}

\end{document}


• Thanks so much. If it is possible to apply your answer to environments such as Exercise or something alike? How to set it up once and for all? – Megadeth Jan 18 '15 at 6:45
• I think, this is possible, but it's a new question, in my point of view. I'll try – user31729 Jan 18 '15 at 6:47
• I tried this \newtheorem{exer}{Exercise}[section] \renewcommand{theexer}{\arabic{exercise}} but it did not work – Megadeth Jan 18 '15 at 6:49
• Much appreciated; I am looking forward to that. :) – Megadeth Jan 18 '15 at 7:05
• @Chou You have to write \renewcommand{\theexer}{\arabic{exer}} – karlkoeller Jan 18 '15 at 7:11