1) 900 − (627 − 58) = 331
2) 250 + 250 + 250 = 750
3) (6 * 9) + (158 + 168) = 380
Вычисления:
900 − (627 − 58) = 900 − 569 = 331
$\begin{array}{r}\begin{array}{r}-\end{array}\underline{\begin{array}{r}627\\ 58\end{array}}\\ \begin{array}{r}569\end{array}\end{array}$
$\begin{array}{r}\begin{array}{r}-\end{array}\underline{\begin{array}{r}900\\ 569\end{array}}\\ \begin{array}{r}331\end{array}\end{array}$
250 + 250 + 250 = 500 + 250 = 750
$\begin{array}{r}\begin{array}{r}+\end{array}\underline{\begin{array}{r}250\\ 250\end{array}}\\ \begin{array}{r}500\end{array}\end{array}$
$\begin{array}{r}\begin{array}{r}+\end{array}\underline{\begin{array}{r}500\\ 250\end{array}}\\ \begin{array}{r}750\end{array}\end{array}$
(6 * 9) + (158 + 168) = 54 + 326 = 380
$\begin{array}{r}\begin{array}{r}+\end{array}\underline{\begin{array}{r}158\\ 168\end{array}}\\ \begin{array}{r}326\end{array}\end{array}$
$\begin{array}{r}\begin{array}{r}+\end{array}\underline{\begin{array}{r}54\\ 326\end{array}}\\ \begin{array}{r}380\end{array}\end{array}$