# How do I customise my section numbering to start from 2.1?

So these sections are to occur at the same level using only \section. Except section numbering will start from 1, and go to 2, 3, 4... etc. which is not what I want. What I was is:

2.1 Summary 2.2 Inventors 2.3 Innovation 2.4 World Patent Coverage 2.5 Advantages 2.6 Limitations 2.7 Patent Challenges 2.8 Market applications and opportunities 2.9 Exploitation 2.10 Clinical Trials 2.11 References

\documentclass[a4paper,12pt]{article}
\usepackage[a4paper]{geometry}
\date{April 1, 2012}
\begin{document}
\title{Patrys}
\maketitle

\section{Summary}
\section{Inventors}
\section{Innovation}
\section{World Patent Coverage}
\section{Limitations}
\section{Patent Challenges}
\section{Market Applications and Opportunities}
\section{Exploitation}
\section{Clinical Trials}
\section{References}

\end{document}

-

\renewcommand{\thesection}{2.\arabic{section}}