\documentclass[10pt]{article}
\bibliographystyle{iopart-num}

\begin{document}

\title{Test document for iopart-num
with the article document class}

\author{M~A~Caprio}

\maketitle

\section{Introduction}

This file may be used to test the iopart-num BibTeX style.
This version of the file is for use with the article document class.

\nocite{*}

\bibliography{iopart-num-example}

\end{document}