Problem:
How many positive perfect squares less than are divisible by ?
Answer Choices:
A.
B.
C.
D.
E.
Solution:
Because 5 is prime, a perfect square is divisible by 5 if and only if its square root is divisible by 5 . Note that , so , and are the only positive perfect squares satisfying the given condition. There are such numbers.
The problems on this page are the property of the MAA's American Mathematics Competitions