Условие:

346 + 458;
157 + 484;
832 − 456;
621 − 241;
503 + 204;
308 + 106;
603 − 28;
204 − 39.

346 + 458 = 804
$\begin{array}{r}\begin{array}{r}+\end{array}\underline{\begin{array}{r}346\\ 458\end{array}}\\ \begin{array}{r}804\end{array}\end{array}$
 
157 + 484 = 641
$\begin{array}{r}\begin{array}{r}+\end{array}\underline{\begin{array}{r}157\\ 484\end{array}}\\ \begin{array}{r}641\end{array}\end{array}$
 
832 − 456 = 376
$\begin{array}{r}\begin{array}{r}-\end{array}\underline{\begin{array}{r}832\\ 456\end{array}}\\ \begin{array}{r}376\end{array}\end{array}$
 
621 − 241 = 380
$\begin{array}{r}\begin{array}{r}-\end{array}\underline{\begin{array}{r}621\\ 241\end{array}}\\ \begin{array}{r}380\end{array}\end{array}$
 
503 + 204 = 707
$\begin{array}{r}\begin{array}{r}+\end{array}\underline{\begin{array}{r}503\\ 204\end{array}}\\ \begin{array}{r}707\end{array}\end{array}$
 
308 + 106 = 414
$\begin{array}{r}\begin{array}{r}+\end{array}\underline{\begin{array}{r}308\\ 106\end{array}}\\ \begin{array}{r}414\end{array}\end{array}$
 
603 − 28 = 575
$\begin{array}{r}\begin{array}{r}-\end{array}\underline{\begin{array}{r}603\\ 28\end{array}}\\ \begin{array}{r}575\end{array}\end{array}$
 
204 − 39 = 165
$\begin{array}{r}\begin{array}{r}-\end{array}\underline{\begin{array}{r}204\\ 39\end{array}}\\ \begin{array}{r}165\end{array}\end{array}$