\documentclass[screen, aspectratio=43]{beamer}
\usepackage[T1]{fontenc}
\usepackage[utf8]{inputenc}

% Use the NTNU-temaet for beamer 
% \usetheme[style=ntnu|simple|vertical|horizontal, 
%     language=bm|nn|en, 
%     smalltitle, 
%     city=all|trondheim|alesund|gjovik]{ntnu2017}
\usetheme[style=ntnu,language=en]{ntnu2017}

\usepackage[english]{babel}
\usepackage[style=numeric,backend=biber,natbib=false,sorting=none]{biblatex}

\title[Short title]{The full and long title of the presentation}
\subtitle{Subtitle if you want}
\author[O. Nordmann]{Ola Nordmann}
\institute[NTNU]{Department of \LaTeX-ical sciences, NTNU}
\date{1 January 1970}
%\date{} % To have an empty date

\addbibresource{example.bib} % Add bibliography database

% Set the reference style to numeric.
% See here: http://tex.stackexchange.com/questions/68080/beamer-bibliography-icon
\setbeamertemplate{bibliography item}[text] 

% Set bibliography fonts to a small size.
\renewcommand*{\bibfont}{\footnotesize}

\begin{document}

\begin{frame}
  \titlepage
\end{frame}

% Alternatively, special title page command to get a different background
% \ntnutitlepage

\begin{frame}
  \frametitle{Main theorem}
  \begin{theorem}
    {\LaTeX} makes things easier.
  \end{theorem}
  \begin{proof}
    For details, see Flynn~\cite{latex}.
  \end{proof}
\end{frame}

\begin{frame}
  \frametitle{References}
  \printbibliography
\end{frame}

\end{document}