David Koretz has his own method of screening job candidates. He gives them brainteasers. Here is one of Koretz's favorites, which is attributed to Albert Einstein.

Who owns the fish?
There are five houses in a row and in five different colors. In each house lives a person from a different country. Each person drinks a certain drink, smokes a certain cigar, and keeps a certain pet. No two people drink the same drink, smoke the same cigar, or keep the same pet.

  • The Brit lives in a red house.
  • The Swede keeps dogs.
  • The Dane drinks tea.
  • The green house is on the left of the white house.
  • The green house owner drinks coffee.
  • The person who smokes Pall Mall rears birds.
  • The owner of the yellow house smokes Dunhill.
  • The man living in the house right in the center drinks milk.
  • The Norwegian lives in the first house.
  • The man who smokes Blend lives next to the man who keeps cats.
  • The man who keeps horses lives next to the one who smokes Dunhill.
  • The man who smokes Bluemaster drinks beer.
  • The German smokes Prince.
  • The Norwegian lives next to the blue house.
  • The man who smokes Blend has a neighbor who drinks water.

Read the article in the May 2001 issue of Inc. about David Koretz: "The Billionaire Next Door."