Throw in "I gave it to a mathematician and he couldn't solve it either" and you've got an instant viral hit, apparently.
All right, rant over.
What's the error?
Oh, and solve it if you want, too. It's not really that hard.
- Which blanks CANNOT have a prime number in them?
- Which blanks COULD have certain prime numbers?
- Which blanks essentially force this problem to be non-unique?
(answer linked from there)