I must confess I don't understand the meaning of the +
symbols in a table devoted to multiplication operations. I therefore omit them from the following solution.
The solution provides two LaTeX macros. The main macro is called \mytab
, and it takes four arguments: the two integers in the top row of the tabular
environment, and the two integers in the left-hand column. There's also an auxiliary macro called \mply
(short for "multiply", I suppose) that performs the multiplication operations.

\documentclass{article}
\usepackage{array}
\newcommand\mply[2]{\the\numexpr#1*#2}
\newcommand\mytab[4]{%
\begingroup
\renewcommand{\arraystretch}{2}
\setlength{\tabcolsep}{12pt} % default: 6pt
\begin{tabular}{| r | r r|}
\cline{2-3}
\multicolumn{1}{c|}{} & #1 & #2 \\
\hline
#3 & \mply{#1}{#3} & \mply{#2}{#3} \\
#4 & \mply{#1}{#4} & \mply{#2}{#4} \\
\hline
\end{tabular}
\endgroup}
\begin{document}
\mytab{30}{7}{20}{3}
\medskip
\mytab{10}{40}{8}{15}
\end{document}
\begin{tabular}{c c c | c} & 30 & + & 7 \\\hline 20 & 600 & & 140 \\ + & & & \\\hline 3 & 90 & & 21 \\\hline \end{tabular}