Thirteen men once agreed to meet at a fixed place and at a certain hour. At the appointed hour they all appeared except one. He was five minutes late. When he arrived, one of the others said, 'You have caused us to lose an hour.'

Looking at his watch, the man who was late said: 'No, only five minutes.'

The other replied: 'There are twelve of us waiting on you, and twelve times five minutes make sixty minutes. So we have lost an hour.'