[Tex/LaTex] How to make siunitx’s \num bold

Question

What I want:

Minimal Example

\documentclass[a4paper]{scrartcl}
\usepackage[ngerman]{babel}
\usepackage[utf8]{inputenc}
\usepackage{amssymb,amsmath}
\usepackage{booktabs}
\usepackage[binary-units,group-separator={,}]{siunitx}
\sisetup{per-mode=fraction,
         binary-units=true,
         group-separator = {\,},
         range-phrase=-}
\DeclareSIUnit\pixel{px}
\DeclareSIUnit\float{float}
\DeclareSIUnit\floats{floats}

\begin{document}

\begin{table}[ht]
    \centering
    \begin{tabular}{cllrrl}
    \toprule
    \# & Type                     & \parbox[t]{3cm}{Filters @\par Patch size / stride} & Parameters & FLOPs & Output size  \\\midrule
       & Input                    &                                           &          0  &            0 & \hphantom{0}1 @ $32\times 32$    \\
    1  & Convolution              & \hphantom{0}6 @ $5 \times 5 \times 1$ / 1 &        156  & \num{307800} & \hphantom{0}\bf{6}\,@\,$\mathbf{28\times 28}$    \\
    2  & Scaled average pooling   & \hphantom{00 @} $2 \times 2 \hphantom{\times 00}$ / 2 &          2  &    \num{336} & \hphantom{0}6 @ $14\times 14$    \\
    3  & Convolution              & 16 @ $5 \times 5 \times 6$ / 1            &  \num{2416} & \bf{\num{942400}} & 16 @ $10\times 10$ \\
    4  & Scaled average pooling   & \hphantom{00 @} $2 \times 2 \hphantom{\times 00}$ / 2 &          2  &   \num{1600} & 16 @ \hphantom{0}$5\times \hphantom{0}5$   \\
    5  & Fully Connected          & 120 neurons                      & \ensuremath{\boldmath\num{48120}} & \num{240000} & 120 \\
    6  & Fully Connected          & \hphantom{0}84 neurons           & \num{10164} &  \num{20580} & \hphantom{0}84 \\
    7  & Fully Connected (output) & \hphantom{0}10 neurons           &        850  &   \num{1730} & \hphantom{0}10 \\\midrule
    $\sum$ &                      &                                  & \num{61710} &\num{15144446}& \num{9118}\\
    \bottomrule
    \end{tabular}
\end{table}
\end{document}

What I tried

I've tried putting \num into math mode and \mathbf / \boldmath, \bf, \bfseries. Nothing worked.

Answer 1

Not perfectly aligned since bold fonts are wider than non bold. Bold fonts are achieved by siunitx package option detect-weight and use of S column type in third and fourth column:

\documentclass[a4paper]{scrartcl}
\usepackage[ngerman]{babel}
\usepackage[utf8]{inputenc}
\usepackage{amssymb,amsmath}
\usepackage{booktabs, makecell}
\renewcommand\theadfont{\normalsize}
\usepackage[binary-units,group-separator={,}]{siunitx}
\sisetup{per-mode=fraction,
         binary-units=true,
         group-separator = {\,},
         range-phrase=-}
\DeclareSIUnit\pixel{px}
\DeclareSIUnit\float{float}
\DeclareSIUnit\floats{floats}

\usepackage{etoolbox}% <-- for bold fonts
\newcommand{\ubold}{\fontseries{b}\selectfont}% <-- for bold fonts
\robustify\ubold% <-- for bold fonts

\begin{document}

\begin{table}[ht]
    \centering
    \begin{tabular}{cll 
                    S[detect-weight,group-minimum-digits = 4,table-format=5.0]% <-- changed
                    S[detect-weight,group-minimum-digits = 4,table-format=8.0]% <-- changed
                    l}
    \toprule
\# &    Type                     
        &   \thead[tl]{Filters @\\ Patch size / stride} 
            &   {Parameters}    &   {FLOPs}   & Output size  \\\midrule
   &    Input                    
        &   &           0       &       0   & \hphantom{0}1 @ $32\times 32$    \\
1  &    Convolution              
        &   \hphantom{0}6 @ $5 \times 5 \times 1$ / 1 
            &       156         &   307 800 & \hphantom{0}\textbf{6}\,@\,$\mathbf{28\times 28}$    \\
2  &    Scaled average pooling   
        & \hphantom{00 @} $2 \times 2 \hphantom{\times 00}$ / 2 
            &        2          &       336 & \hphantom{0}6 @ $14\times 14$    \\
3  &    Convolution              
        &   16 @ $5 \times 5 \times 6$ / 1            
            &   2 416           & \ubold 942 400% <-- boldface
                                    & 16 @ $10\times 10$ \\
4  &    Scaled average pooling   
        &   \hphantom{00 @} $2 \times 2 \hphantom{\times 00}$ / 2 
            &        2          &     1 600 & 16 @ \hphantom{0}$5\times \hphantom{0}5$   \\
5  &    Fully Connected          
        &   120 neurons                      
            & \ubold 48 120% <-- boldface
                & 240 000   & 120 \\
6  &    Fully Connected          
        &   \hphantom{0}84 neurons           
                &       10 164  &   20 580  & \hphantom{0}84 \\
7  & Fully Connected (output) 
        &   \hphantom{0}10 neurons           
            &               850 &   1 730   & \hphantom{0}10 \\ \midrule
$\sum$  &   &   &        61 710 & 15 144 446& \num{9118}\\
    \bottomrule
    \end{tabular}
\end{table}
\end{document}

Note: use of \bf is depreciated for + 20 years.

Edit:

Meanwhile (after many years and comments below) many of us learned how to managed boldface digits in S column tables. In original answer was not added option mode=text to \sisetup and definition of ubold can also be improved:

% preamble as before
\usepackage{etoolbox}% <-- for robustify bold fonts in S columns
\newrobustcmd\ubold{\DeclareFontSeriesDefault[rm]{bf}{b}\bfseries}% <-- changed

\begin{document}
    \begin{table}[ht]
    \centering
\sisetup{detect-weight,
         group-minimum-digits = 4,
         mode=text    % <--- added
         }
    \begin{tabular}{cll
                    S[table-format=5.0]% <-- changed
                    S[table-format=8.0]% <-- changed
                    l}
% table body

Considering above in MWE gives desired result: