Five couples attend a social function. They all arrive at approximately the same time and start greeting each other. After half and hour, Bob one of the husbands stands up and gets everyone's attention. He goes round the room asking the other guests how many times they shook hands. To everyone's amazement everyone that Bob asked had shaken hands a different number of time.

"The question is: How many times did Bob shake hands?"

That's all the clues and there's only one solution!