Условие:

Вычисли устно.
126 + 3
402 + 7
205 + 5
250 + 50
180 + 16
134 + 200
754 − 4
821 − 21
936 − 900

126 + 3 = 129
402 + 7 = 409
205 + 5 = 210
250 + 50 = 300
180 + 16 = 196
134 + 200 = 334
754 − 4 = 750
821 − 21 = 800
936 − 900 = 36
Вычисления:
$\begin{array}{r}\begin{array}{r}+\end{array}\underline{\begin{array}{r}126\\ 3\end{array}}\\ \begin{array}{r}129\end{array}\end{array}$
$\begin{array}{r}\begin{array}{r}+\end{array}\underline{\begin{array}{r}402\\ 7\end{array}}\\ \begin{array}{r}409\end{array}\end{array}$
$\begin{array}{r}\begin{array}{r}+\end{array}\underline{\begin{array}{r}205\\ 5\end{array}}\\ \begin{array}{r}210\end{array}\end{array}$
$\begin{array}{r}\begin{array}{r}+\end{array}\underline{\begin{array}{r}250\\ 50\end{array}}\\ \begin{array}{r}300\end{array}\end{array}$
$\begin{array}{r}\begin{array}{r}+\end{array}\underline{\begin{array}{r}180\\ 16\end{array}}\\ \begin{array}{r}196\end{array}\end{array}$
$\begin{array}{r}\begin{array}{r}+\end{array}\underline{\begin{array}{r}134\\ 200\end{array}}\\ \begin{array}{r}334\end{array}\end{array}$
$\begin{array}{r}\begin{array}{r}-\end{array}\underline{\begin{array}{r}754\\ 4\end{array}}\\ \begin{array}{r}750\end{array}\end{array}$
$\begin{array}{r}\begin{array}{r}-\end{array}\underline{\begin{array}{r}821\\ 21\end{array}}\\ \begin{array}{r}800\end{array}\end{array}$
$\begin{array}{r}\begin{array}{r}-\end{array}\underline{\begin{array}{r}936\\ 900\end{array}}\\ \begin{array}{r}36\end{array}\end{array}$