$1 \quad$ How many zeroes does the product of $25^{5}, 150^{4}$ and $2008^{3}$ end with?
(A) 5
(B) 9
(C) 10
(D) 12
(E) 13
1. Answer: (E) $25^{5}=5^{10}, 150^{4}=2^{4} \times 3^{4} \times 5^{8}$ and $2008^{3}=2^{9} \times 251^{3}$. So the product contains factors $2^{13}$ and $5^{18}$, which produce $10^{13}$.