33.64 If the number 15! is expressed in base 12, its size ends with $k$ zeros, and when expressed in base 10, its size ends with $h$ zeros, then $k+h$ equals
(A) 5.
(B) 6.
(C) 7.
(D) 8.
(E) 9.
(16th American High School Mathematics Examination, 1965)
[Solution] $15!=10^{3}(3 \cdot 14 \cdot 13 \cdot 12 \cdot 11 \cdot 9 \cdot 8 \cdot 7 \cdot 6 \cdot 3 \cdot 2 \cdot 1)$,
$$
15!=12^{5}(15 \cdot 14 \cdot 13 \cdot 11 \cdot 5 \cdot 7 \cdot 5) \text {. }
$$

Therefore, $k=5, h=3$, so $k+h=8$.
Hence, the answer is $(D)$.