4. The number 987654321 is multiplied by 9 . How many times does the digit 8 occur in the result?
A 1
B 2
C 3
D 4
E 9
Solution
E There does not seem to be any better way to answer this question than to do the multiplication:
$$
\begin{array}{r}
987654321 \\
\times 9 \\
\hline 8888888889
\end{array}
$$

From this we see that the digit 8 occurs 9 times in the answer.
FOR INVESTIGATION
4.1 Try the following multiplications which have surprising answers:
(a) $127 \times 9721$,
(b) $32800328 \times 271$,
(c) $239 \times 4649$,
(d) $21649 \times 513239$.
4.2 Find some other examples of a similar type.