Question 8
In the addition problem below, $A$ and $B$ are nonzero digits:
$$
\begin{array}{r} 9876 \\ A32 \\ +B1 \\ \hline \end{array}
$$
How many digits (not necessarily different) are in the sum of the three whole numbers?
$$
\begin{array}{r} 9876 \\ A32 \\ +B1 \\ \hline \end{array}
$$
How many digits (not necessarily different) are in the sum of the three whole numbers?