Problem:
In how many ways can be written as the sum of two primes?
Answer Choices:
A.
B.
C.
D.
E. more than
Solution:
It is not possible to write as the sum of two primes. When is written as the sum of two whole numbers, one must be even and the other odd. Since is the only even prime, there is only one case to consider. In that case, the other summand must be which is not a prime since it has a factor of .
Answer: .
The problems on this page are the property of the MAA's American Mathematics Competitions