A white number inside a black circle.
Created from this answer linked in the question above.
\documentclass{article}
\usepackage{tikz}
\usepackage{xcolor}
\newcommand*\circled[1]{\tikz[baseline=(char.base)]{
\node[shape=circle,fill,inner sep=2pt] (char) {\textcolor{white}{#1}};}}
\begin{document}
\circled{1}
\end{document}
In what context do you want to use the numbers?
This does work in many situations. Observe that the color of the number and the circle are chosen automatically.
\documentclass{memoir}
\usepackage{tikz}
\newcommand{\ballnumber}[1]{\tikz[baseline=(myanchor.base)] \node[circle,fill=.,inner sep=1pt] (myanchor) {\color{-.}\bfseries\footnotesize #1};}
\begin{document}
Earum excepturi inventore necessitatibus aliquid reiciendis enim. \ballnumber{37} Earum excepturi inventore necessitatibus aliquid reiciendis enim.
\end{document}
Edit:The question Good way to make \textcircled numbers? is related.