I thought this was a good one. All my friends who I've shown it to (except for one) haven't been able to solve it. Many years from now, two men are sitting in the county park. The following is part of their discussion: Man 1: Yes, I'm married and have three fine sons. Man 2: That's wonderful! How old are they? MaN 1: Well, The product of their ages is equal to 36. Man 2: Hmm. That doesn't tell me enough. Give me another clue. Man 1: Ok, the sum of their ages is the number on that building across the street. Man 2: A ha! I've almost got the answer, but I still need another clue. Man 1: Very well. The oldest one has red hair. Man 2: I've got it!