917 − 828 = 89
$\begin{array}{r}\begin{array}{r}-\end{array}\underline{\begin{array}{r}917\\ 828\end{array}}\\ \begin{array}{r}89\end{array}\end{array}$
 
218 − 159 = 59
$\begin{array}{r}\begin{array}{r}-\end{array}\underline{\begin{array}{r}218\\ 159\end{array}}\\ \begin{array}{r}59\end{array}\end{array}$
 
58 + 642 + 87 = 787
$\begin{array}{r}\underline{\begin{array}{r}\text{58}\\ \text{+642}\\ \text{+87}\end{array}}\\ \hfill \text{787}\hfill \end{array}$
 
89 + 372 + 28 = 489
$\begin{array}{r}\underline{\begin{array}{r}\text{89}\\ \text{+372}\\ \text{+28}\end{array}}\\ \hfill \text{489}\hfill \end{array}$
 
900 − 638 = 262
$\begin{array}{r}\begin{array}{r}-\end{array}\underline{\begin{array}{r}900\\ 638\end{array}}\\ \begin{array}{r}262\end{array}\end{array}$
 
604 − 187 = 417
$\begin{array}{r}\begin{array}{r}-\end{array}\underline{\begin{array}{r}604\\ 187\end{array}}\\ \begin{array}{r}417\end{array}\end{array}$
 
199 * 5 = 995
$\begin{array}{r}\times \underset{¯}{\begin{array}{r}199\\ 5\end{array}}\\ 995\end{array}$
 
68 * 9 = 612
$\begin{array}{r}\times \underset{¯}{\begin{array}{r}68\\ 9\end{array}}\\ 612\end{array}$