The last two digits of $33 \cdot 92025^{1989}$ are
(A) 15.
(B) 25.
(C) 45.
(D) 55.
(1st "Five Sheep Cup" Junior High School Mathematics Competition, 1989)
[Solution] The last two digits of any power of an integer ending in 25 are always 25. Therefore, the answer is (B).