Suppose you overheard the following conversation:
William: I have three children.
Harry: What are their ages?
William: The product of their ages is 36.
Harry: I can’t determine their ages.
William: The sum of their ages is your apartment number.
Harry: I still can’t do it.
William: The oldest plays football.
Harry: OK, now I know their ages.
Determining the ages of the three children is possible from this information. What are they?