I'm trying to define a new counter which does the following:
\documentclass[10pt]{article}
\usepackage{amsmath}
\usepackage{amssymb}
\usepackage{array}
\usepackage{tikz}
\usepackage{longtable}
\newcommand*\circled[1]{\tikz[baseline=(char.base)]{
\node[shape=circle,draw,inner sep=2pt] (char) {#1};}}
\begin{document}
\begin{longtable}{lll}
\circled{x} \quad $3x^4-x^4-x^3(x+2)$ &
\circled{x} \quad $-12a^2+3a(a+1)$ &
\circled{x} \quad $ax^n+4x^n$
\end{longtable}
\end{document}
In the circles there should be 1., 2. and so on.
Is it possible to define a counter which counts automaticly?