39 * (641 − 5720 : 13) = 39 * (641 − 440) = 39 * 201 = 7839
$\begin{array}{cc}\begin{array}{l}\underset{¯}{\phantom{0}}5720\\ \phantom{0}\underset{¯}{52}\\ \phantom{0}\underset{¯}{\phantom{0}}52\\ \phantom{00}\underset{¯}{52}\\ \phantom{000}\underset{¯}{\phantom{0}}0\\ \phantom{0000}\underset{¯}{0}\\ \phantom{0000}0\end{array}& \begin{array}{l}\overline{)13}\\ \overline{\overline{)440}}\end{array}\end{array}$
 
$\begin{array}{r}\times \underset{¯}{\begin{array}{r}39\\ 201\end{array}}\\ 39\\ 0\phantom{0}\\ 78\phantom{00}\\ \overline{7839}\end{array}$

$5\ast <!--\; \ast \; -->{10}^3=5\ast <!--\; \ast \; -->1000=5000$

$(15+9{)}^2={24}^2=576$
$\begin{array}{r}\times \underset{¯}{\begin{array}{r}24\\ 24\end{array}}\\ 96\\ 48\phantom{0}\\ \overline{576}\end{array}$