(449 + 356) + 51 = 856
Вычисления:
(449 + 356) + 51 = 805 + 51 = 856
$\begin{array}{r}\begin{array}{r}+\end{array}\underline{\begin{array}{r}449\\ 356\end{array}}\\ \begin{array}{r}805\end{array}\end{array}$
$\begin{array}{r}\begin{array}{r}+\end{array}\underline{\begin{array}{r}805\\ 51\end{array}}\\ \begin{array}{r}856\end{array}\end{array}$

(609 − 247) − 63 = 299
Вычисления:
(609 − 247) − 63 = 362 − 63 = 299
$\begin{array}{r}\begin{array}{r}-\end{array}\underline{\begin{array}{r}609\\ 247\end{array}}\\ \begin{array}{r}362\end{array}\end{array}$
$\begin{array}{r}\begin{array}{r}-\end{array}\underline{\begin{array}{r}362\\ 63\end{array}}\\ \begin{array}{r}299\end{array}\end{array}$