\documentclass[a4j,10pt,papersize]{jsarticle}
\newcommand*\mypict{\setlength\unitlength{1pt}%
  \begin{picture}(40,40)%
    \put(20,20){\circle*{10}}%
    \put(20,20){\circle{20}}%
  \end{picture}}%
\usepackage{multicol}
\columnseprule=.4pt
\columnsep=2zw
\multicolsep=1zw
\makeatletter
\def\myfigure{\vbox\bgroup\centering\def\@captype{figure}}
\def\mytable{\vbox\bgroup\centering\def\@captype{table}}
\def\endmyfigure{\egroup}
\def\endmytable{\egroup}
\def\hoge{\@tempcnta=\z@ \@whilenum \@tempcnta<100\do{%
   ほげほげ\advance\@tempcnta\@ne}。}
\makeatother
\begin{document}
\hoge
\begin{multicols}{3}
\hoge
\begin{equation}
 f(x)  = ax +b
\end{equation}
\hoge
\begin{figure*}[tb]
\centering\mypict
\caption{普通の\texttt{figure}環境での図だよ}
\end{figure*}
\hoge
\begin{myfigure}
 \mypict
 \caption{\texttt{multicols}環境中の図だよ}
\end{myfigure}
\hoge
\begin{mytable}
\begin{small}
  \caption{\texttt{multicols}環境中の表だよ}
 \begin{tabular}{lll}
 \hline
 \LaTeX & \LaTeXe& \LaTeX\,3\\
 \hline
 \end{tabular}
\end{small}
\end{mytable}
\hoge
\end{multicols}
\hoge
\begin{multicols}{4}[\section{新聞記事とか色々あるけどねぇ、どうだろう。}]
\hoge
\end{multicols}
\hoge
\begin{multicols}{5}
\hoge\par \hoge
\end{multicols}
\hoge 
\begin{multicols}{7}
\hoge\par \hoge
\end{multicols}
\end{document}
