%%
%% The LaTeX Companion, 3ed
%%
%% Example 6-7-19 on page I-487 in "siunitx --- Scientific numbers in tables".
%%
%% 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{123.0pt}
\setlength\parindent{0pt}
%StartShownPreambleCommands
\usepackage{siunitx}
%StopShownPreambleCommands

\begin{document}
\sisetup{table-auto-round}
\begin{tabular}{|S[table-format=-2.3]|S[table-format=-2.1]|}
 {Header} & {Header} \\
 -47.11 & -47.11 \\ 1.2 & 1.2 \\ 10.2754 & 10.2754
\end{tabular}
\end{document}