%%
%% The LaTeX Companion, 3ed
%%
%% Example 3-3-23 on page I-169 in "Basic number and unit formatting".
%%
%% Copyright (C) 2022 Frank Mittelbach
%%
%% It may be distributed and/or modified under the conditions
%% of the LaTeX Project Public License, either version 1.3c
%% of this license or (at your option) any later version.
%%
%% See https://www.latex-project.org/lppl.txt for details.
%%

\documentclass{tlc3exa}
\pagestyle{empty}
\setcounter{page}{6}
\setlength\textwidth{111.0pt}
\setlength\parindent{0pt}
%StartShownPreambleCommands
\usepackage{siunitx,xfrac}
\newcommand\sample[1]{#1:\quad \unit{\kilo\metre\per\hour}
                     \hfill\unit{\mole\per\metre\cubed}\\[5pt]}
%StopShownPreambleCommands

\begin{document}
                                                    \sample{A}
\sisetup{per-mode=symbol}                           \sample{B}
\sisetup{per-mode=fraction}                         \sample{C}
\sisetup{per-mode=fraction,fraction-command=\sfrac} \sample{D}
\end{document}