Problem:
What is the tens digit of
Answer Choices:
A.
B.
C.
D.
E.
Solution:
The tens digit of a power of is determined by the last two digits of the previous power of . The pattern for the last two digits of successive powers of is Since , the last two digits of are and the tens digit is .
Answer: .
The problems on this page are the property of the MAA's American Mathematics Competitions