Riddle: Once, there was a billionaire who owned a circular house. Everything was circles. But one morning, the billionaire was found dead on the floor. The police questioned three people. The cook, the butler, and the guard. The guard said he was doing his own job (guarding the house) when he heard a bashing sound inside. The cook said he was busy making breakfast when he got the news. Finally, the butler said he was sweeping the corners of the house. Who killed the billionaire?
Answer: The butler. There's no corners in a circle.