Ann: How old are your three kids, again?
Bob: The product of their ages is 36.
Ann: I can't figure it out from that information.
Bob: The sum of their ages is the same as your house number.
Ann: That's still not enough information.
Bob: The one who's older than the others has red hair.
Ann: Thanks! Now I've got it.
How old are Bob's kids?
Source: Tony Zhou (via Richard Neal)