Skip to main content
OlympiadHQ

Browse · MATH

Print

jmc

number theory intermediate

Problem

Find the units digit of
Solution
Since the tens digits don't matter to us, the problem is the same as finding the units digit of . Now we go hunting for the pattern of units digits of powers of 3: The cycle of units digits is 4 long. Since , we know that has the same units digit as .
Final answer
3