# Formatting arrows and text under a matrix

I am looking to be able to write this: https://imgur.com/a/FFMifhs

but I'm a little stuck with the arrows and what not concerning the arrows underneath the matrix. I've got this so far:

 \begin{pmatrix}
1 & 2 & 3 & 4 \\
\square & \square & \square & \square
\\   $\uparrow$
\end{pmatrix}


Thanks for the help.

\documentclass{article}
\usepackage{amsmath,amssymb,tikz}
\newcommand{\Poss}[1]{\ifnum#1=1
\tikz[remember picture]{\node(node-#1){$\scriptscriptstyle \begin{array}{c}#1~\text{possi-}\\ \text{bility}\end{array}$}}
\else
\tikz[remember picture]{\node(node-#1){$\scriptscriptstyle \begin{array}{c}#1~\text{possi-}\\ \text{bilities}\end{array}$}}
\fi}
\begin{document}
$\begin{pmatrix} 1 & 2 & 3 & 4 \\ \square & \square & \square & \square \\ \uparrow & \uparrow &\uparrow &\uparrow \\ \Poss{4} & \Poss{3} & \Poss{2} & \Poss{1} \\[-1.6cm] \end{pmatrix}$
\tikz[overlay,remember picture]{\foreach \X [count=\Y] in {2,3,4}
{\path (node-\Y) -- (node-\X) node[midway]{$\scriptstyle\times$};}}
\end{document}


• Brilliant, thanks so much. Never would have got this! – Zombiegit123 Aug 8 '18 at 22:43
• @marmot -- if it doesn't throw off the alignment too much, a much better word break would be "possi-bilities" – barbara beeton Sep 17 '18 at 16:05
• @barbarabeeton Thanks, you are right. The language of humans will always remain difficult for me, ;-) – marmot Sep 17 '18 at 16:11

You could use the tabular environment instead of a matrix. Here is my solution:

\documentclass{article}

\usepackage{amsmath}
\usepackage{amssymb}
\usepackage{multirow}
\usepackage{array}

\begin{document}

\begin{tabular}{ccccccc}

\multirow{2}{*}{$\biggl($}

& 1 & 2 & 3 & 4 &

\multirow{2}{*}{$\biggr)$} \\
& $\square$  & $\square$  & $\square$  & $\square$  & &\\
& $\uparrow$ & $\uparrow$ & $\uparrow$ & $\uparrow$ & &\\
& \multicolumn{1}{c!{\makebox[0pt]{$\times$}}}{\parbox{7ex}{\small 4 possibilities}}
& \multicolumn{1}{c!{\makebox[0pt]{$\times$}}}{\parbox{7ex}{\small 3 possibilities}}
& \multicolumn{1}{c!{\makebox[0pt]{$\times$}}}{\parbox{7ex}{\small 2 possibilities}}
& {\parbox{7ex}{\small 1 possibilities}}
& =
& $4!$ possibilities \\
\end{tabular}

\end{document}


This is what I obtain:

• Good +1. Can you edit your answer because possibilities is not in math mode? – Sebastiano Aug 8 '18 at 22:32