\chapter{Chapter with equations}
\label{chap:chapter_1}

This is the first equation:
\begin{equation}
  1 + 1 = 2.
  \label{eq:1}
\end{equation}

\noindent
This is the second equation:
\begin{equation}
  1 \times 1 = 1.
  \label{eq:2}
\end{equation}
