\documentclass{article}

\begin{document}

\section{Introduction}

This document...

Make sure the equation numbers are not 1.
\begin{equation}
  1+1=2
  \label{eqn:foo}
\end{equation}
\begin{equation}
  42+1=43
  \label{eqn:bar}
\end{equation}

\section{Euler's equation}
\label{sec:euler}

Euler's equation
\begin{equation}
  e^{i\phi} = \cos\phi + i\sin\phi.
  \label{eqn:euler}
\end{equation}

\end{document}
