Problem:
The remainder when the product is divided by is
Answer Choices:
A.
B.
C.
D.
E.
Solution:
The last digit of a product is determined by the product of the last digits of the factors. Since , the last digit of the product is . Since multiples of end in or , any number with last digit leaves a remainder of when divided by .
Answer: .
The problems on this page are the property of the MAA's American Mathematics Competitions