(43 + 15) − 10 = 48
(50 − 20) + 42 = 72
(71 + 27) + 1 = 99
(68 − 5) − 2 = 61
Вычисления:
(43 + 15) − 10 = 58 − 10 = 48
$\begin{array}{r}\begin{array}{r}+\end{array}\underline{\begin{array}{r}45\\ 15\end{array}}\\ \begin{array}{r}58\end{array}\end{array}$
$\begin{array}{r}\begin{array}{r}-\end{array}\underline{\begin{array}{r}58\\ 10\end{array}}\\ \begin{array}{r}48\end{array}\end{array}$
(50 − 20) + 42 = 30 + 42 = 72
$\begin{array}{r}\begin{array}{r}-\end{array}\underline{\begin{array}{r}50\\ 20\end{array}}\\ \begin{array}{r}\mathrm{30\text{'}}\end{array}\end{array}$
$\begin{array}{r}\begin{array}{r}+\end{array}\underline{\begin{array}{r}30\\ 42\end{array}}\\ \begin{array}{r}72\end{array}\end{array}$
(71 + 27) + 1 = 98 + 1 = 99
$\begin{array}{r}\begin{array}{r}+\end{array}\underline{\begin{array}{r}71\\ 27\end{array}}\\ \begin{array}{r}98\end{array}\end{array}$
$\begin{array}{r}\begin{array}{r}+\end{array}\underline{\begin{array}{r}98\\ 1\end{array}}\\ \begin{array}{r}99\end{array}\end{array}$
(68 − 5) − 2 = 63 − 2 = 61
$\begin{array}{r}\begin{array}{r}-\end{array}\underline{\begin{array}{r}68\\ 5\end{array}}\\ \begin{array}{r}63\end{array}\end{array}$
$\begin{array}{r}\begin{array}{r}-\end{array}\underline{\begin{array}{r}63\\ 2\end{array}}\\ \begin{array}{r}61\end{array}\end{array}$