Problem:
There are twenty-four -digit whole numbers that use each of the four digits , and exactly once. Listed in numerical order from smallest to largest, the number in the th position in the list is
Answer Choices:
A.
B.
C.
D.
E.
Solution:
One-fourth of the numbers in the list begin with each of the four given digits. Those in positions begin with ; those in positions begin with ; those in positions begin with . Thus the desired number is the fifth one beginning with .
Answer: .
The problems on this page are the property of the MAA's American Mathematics Competitions