$14 \cdot 10$ The numbers from 1 to 9 are written on nine pieces of paper placed in a hat. Jack randomly draws one and puts it back, then Jill also randomly draws one. What is the most likely digit in the units place of the sum of the numbers drawn by Jack and Jill?
(A) 0.
(B) 1.
(C) 8.
(D) 9.
(E) Each digit is equally likely.
(39th American High School Mathematics Examination, 1988)
[Solution] The unit digit of the sum of numbers $1 \sim 9$ and $1 \sim 9$ can be shown in the following table:
\begin{tabular}{|c|c|c|c|c|c|c|c|c|c|}
\hline$\langle m+n\rangle^{m}$ & 1 & 2 & 3 & 4 & 5 & 6 & 7 & 8 & 9 \\
\hline 1 & 2 & 3 & 4 & 5 & 6 & 7 & 8 & 9 & 0 \\
\hline 2 & 3 & 4 & 5 & 6 & 7 & 8 & 9 & 0 & 1 \\
\hline 3 & 4 & 5 & 6 & 7 & 8 & 9 & 0 & 1 & 2 \\
\hline 4 & 5 & 6 & 7 & 8 & 9 & 0 & 1 & 2 & 3 \\
\hline 5 & 6 & 7 & 8 & 9 & 0 & 1 & 2 & 3 & 4 \\
\hline 6 & 7 & 8 & 9 & 0 & 1 & 2 & 3 & 4 & 5 \\
\hline 7 & 8 & 9 & 0 & 1 & 2 & 3 & 4 & 5 & 6 \\
\hline 8 & 9 & 0 & 1 & 2 & 3 & 4 & 5 & 6 & 7 \\
\hline 9 & 0 & 1 & 2 & 3 & 4 & 5 & 6 & 7 & 8 \\
\hline
\end{tabular}

Here $\langle m+n\rangle$ represents the unit digit of $m+n$. From the table, we can see: 0 appears 9 times in the table, and the other digits each appear 8 times.
The maximum possible unit digit of the sum of the two numbers is 0.
Therefore, the answer is $(A)$.