\documentstyle{article}
\begin{document}

\huge
$ a \atop {a+b}$\\
$\begin{array}{c c c}
a & b& c\\
d & e& f\\
\end{array}$
\\
$\left(\begin{array}{c c}
a&b+c\\
d+e&f\\
\end{array}\right)$
\\
$x=\left|\begin{array}{r l}
a  &b\\
c  &d\\
\end{array}\right|$
\\
$x=\left|\begin{array}{rr}
baba  &b\\
c  &d\\
\end{array}\right|$

$\pmatrix{a&b\cr          c&d}$
\begin{tabular}{||| c c||c ||}\hline
name family & exm10 \\ 
&10\\\hline
ali akbari & 9\\ \cline{1-2}
\end {tabular}\\\\\\\\
\begin{tabular}{||| c||c||||c ||}\hline\hline
abc&b&c\\ \cline{2-3}
&$s^2$&y\\ \cline{1-2}
$y_1$&25&Zx\\ \hline
\end {tabular}\\\\\\\\
\begin{tabular}{|c|c|c|} \hline
name&family&exm\\ \hline
\multicolumn{2}{|c|}{$a\quad k$}& 9 \\  \hline
\end {tabular}


\end{document} 