Problem:
The digits , and are used to form four two-digit prime numbers, with each digit used exactly once. What is the sum of these four primes?
Answer Choices:
A.
B.
C.
D.
E.
Solution:
The digits , and cannot be the units digit of any two-digit prime, so these four digits must be the tens digits, and , and are the units digits. The sum is thus
(One set that satisfies the conditions is .)
Answer: .
The problems on this page are the property of the MAA's American Mathematics Competitions