Engineers vs Mathematicians

A group of engineers and a group of mathematicians were on a train to a convention. Each mathematician held a ticket, but the engineers had only one ticket for the whole group. The mathematicians started snickering, wondering how the engineers would get away with it.

Suddenly, one engineer shouted, "Conductor coming!" All the engineers crammed into one restroom. The conductor checked the mathematicians' tickets, then knocked on the restroom door, saying, "Ticket, please." The engineers slid their single ticket under the door, and the conductor punched it and left. The mathematicians were impressed. On the return trip, the mathematicians decided to try the same trick and bought only one ticket. The engineers, however, bought no tickets at all. When the lookout yelled, "Conductor coming!", the mathematicians crowded into one restroom. One of the engineers then knocked on that restroom door and said, "Ticket, please."