I have a booktabs (longtable) and I make a column Order. I have to input the number 1, 2, 3, ... by hand. How can I make a column that the numbers are counted automatically? My code is
\documentclass[12pt,a4paper]{article}
\usepackage[utf8]{inputenc}
\usepackage{amsmath}
\usepackage{array,longtable,fourier}
\usepackage[left=2cm,right=2cm,top=2cm,bottom=2cm]{geometry}
\usepackage{booktabs}
\begin{document}
\begin{longtable}{*{5}{>{$}c<{$}}}
\endfirsthead % blank header on first page
\multicolumn{5}{@{}l}{(\emph{array continued from previous page})}
\endhead
\multicolumn{5}{r@{}}{(\emph{array continued on next page})}
\endfoot
\endlastfoot
\begin{tabular}{@{}cllll@{}}
\toprule[1pt]
Order & point $A$ & point $B$ & point $C$ & point $D$ \\ \midrule
1 & $(1,2,-6)$ & $(1,2,-6)$ & $(1,2,-6)$ & $(1,2,-6)$ \\
2 & $(1,2,-6)$ & $(1,2,-6)$ & $(1,2,-6)$ & $(1,2,-6)$ \\
3 & $(1,2,-6)$ & $(1,2,-6)$ & $(1,2,-6)$ & $(1,2,-6)$ \\ \bottomrule
\end{tabular}
\end{longtable}
\end{document}


tabularinside oflongtableutterly defeats the purpose oflongtable, which is to allow pagebreaks inside the tabular material. – Mico Mar 05 '18 at 09:28$\left (\dfrac{1}{2}, \dfrac{3}{4}\right )$, Can I reduce to \left (\dfrac{1}{2}, \dfrac{3}{4}\right ) (obmit $$) but receive the same result? – minhthien_2016 Mar 05 '18 at 09:40\left( \dfrac{1}{2}, \dfrac{3}{4} \right)in various cells. However, I don't think it's a good idea to use\dfracin tabular material. Why not use inline-fraction notation, i.e.,(1/2, 3/4)? – Mico Mar 05 '18 at 09:55