Вариант 1
910 − a
Если a = 49:
910 − a = 910 − 49 = 861
$\begin{array}{r}\begin{array}{r}-\end{array}\underline{\begin{array}{r}910\\ 49\end{array}}\\ \begin{array}{r}861\end{array}\end{array}$
Если a = 510:
910 − a = 910 − 510 = 400
$\begin{array}{r}\begin{array}{r}-\end{array}\underline{\begin{array}{r}910\\ 510\end{array}}\\ \begin{array}{r}400\end{array}\end{array}$
Если a = 896:
910 − a = 910 − 896 = 14
$\begin{array}{r}\begin{array}{r}-\end{array}\underline{\begin{array}{r}910\\ 896\end{array}}\\ \begin{array}{r}14\end{array}\end{array}$
Вариант 2
1 000 − a
Если a = 50:
1 000 − a = 1 000 − 50 = 950
$\begin{array}{r}\begin{array}{r}-\end{array}\underline{\begin{array}{r}1000\\ 50\end{array}}\\ \begin{array}{r}950\end{array}\end{array}$
Если a = 380:
1 000 − a = 1 000 − 380 = 620
$\begin{array}{r}\begin{array}{r}-\end{array}\underline{\begin{array}{r}1000\\ 380\end{array}}\\ \begin{array}{r}620\end{array}\end{array}$
Если a = 997:
1 000 − a = 1 000 − 997 = 3
$\begin{array}{r}\begin{array}{r}-\end{array}\underline{\begin{array}{r}1000\\ 997\end{array}}\\ \begin{array}{r}3\end{array}\end{array}$