An infinite number of mathematicians walk into a bar. The first one orders a beer. The second orders half a beer. The third, a quarter of a beer. The bartender says "You're all idiots", and pours two beers.
Heisenberg got pulled over for speeding. The cop says "Do you know how fast you were going?" And Heisenberg sayd "No, but I know exactly where I am."
A physicist, a biologist, and a mathematician are assigned to observe a house for one month and report their findings. Two weeks pass and no one is observed entering or leaving the house. Then, one person is observed entering the house. The next day two people emerge.
The physicist says: "Our initial observations were incorrect!"
The biologist says: "They must have reproduced!"
And, the mathematician says: "If one more person enters that house it'll be empty!"
He should have made the guy write it down and compare them, but I really wouldn't know a better way of trying to explain this to the empoyee without starting shouting.