\documentclass[a4paper, article, oneside, norsk, hidelinks, 10pt]{memoir}

%% Smaller margins
\usepackage[margin=1in]{geometry}

%% Encoding
\usepackage[utf8]{inputenc}
\usepackage[T1]{fontenc}

%% Fonts and typography
\usepackage[final]{microtype}         % Improved typography
\usepackage[sfdefault]{ClearSans}     % Sans serif font

%% Miscellanous styling
\pagestyle{empty}                     % Remove page number

% Invoice
\usepackage{simpleinvoice}

\begin{document}

\setname{Navn Navnesen}
\setaddress{Langtvekkveien 13b \\ 0123 Oslo}{Langtvekkveien 13b / 0123 Oslo}
\setaccountnumber{1234 56 78910}
\setourref{Navn Navnesen}
\setemail{mail@domain.no}
\setphonenumber{123 45 678}

\setreceivername{Rik Rikmansen og sønner}
\setreceiveraddress{Pengeveien 342 \\ 9876 Gokk}
\setyourref{Rik Rikmansen}

\setinvoicenumber{38}

\additem{Flere}{5 000.00 kr}{20}{6 000.00 kr}
\additem{Ulike}{8 000.00 kr}{20}{9 600.00 kr}
\additem{Ting}{10 000.00 kr}{20}{12 000.00 kr}

\setsubtotal{23 000.00 kr}
\setvat{4 600.00 kr}
\settotal{27 600.00 kr}

\makeinvoice

\end{document}