Census-taker to lady: How many children do you have?
Lady: Three.
Census-taker: How old are they?
Lady: the product of their ages is 36.
Census-taker: Well, that's just not enough information.
Lady: The sum of their ages is our house number.
Census-taker looks at the house number thinking this would give it away, but says: Still not enough information!.
Lady: My oldest child plays the piano.
Census-taker: AHA! I know now. Thank you!
How did the census-taker figure out their ages? CAN YOU? Don't quit. Start out
by trying some numbers. What are their ages?
For the answer (try not to look right away!).