3 mathematicians and 3 physicists want to go on a train ride

The physicists buy 3 tickets(one for each) and the mathematicians say they have a special method and buy 1 ticket(1 for the 3 of them) On the train the mathematicians lock up in the same toilet and when the conductor knocked and asked for the ticket, one mathematician put his hand out with the ticket and that fooled the conductor On the way back, the physicists divided to use the math method and bought only one ticket. The mathematicians said they have another method and didn’t buy any tickets On the train the physicists lock up in one toilet and the mathematicians in another. Then one mathematician comes out and knocks on the physicists’ toilet. The physicists think that that’s the conductor and pull the ticket out. The mathematician takes the ticket and goes back into the toilet with the other mathematicians Moral: don’t use a mathematical method if you don’t know how it works