A Mathematician, a Physicist and an Engineer entered a mathematics contest, the first task of which was to prove that all odd numbers are prime. That's easy said the Mathematician; "1's a prime, 3's a prime, 5's a prime, 7's a prime. Therefore by mathematical induction, all odd numbers are prime". Then it was the Physicist's turn: "1's a prime, 3's a prime, 5's a prime, 7's a prime, 11's a prime, 13's a prime. So, allowing for experimental error, all odd numbers are prime. The engineer provided the most straightforward proof: "1's a prime, 3's a prime, 5's a prime, 7's a prime, 9's a prime, 11's a prime, 13's a prime . . . ".

There are three types of Mathematician; those who can count, and those who can't.

A Mathematician, a Physicist, and an astronomer were travelling north by train. They had just crossed the border into Scotland, when the Astronomer looked out of the window and saw a single black sheep in the middle of a field.
"All Scottish sheep are black," he remarked. "No, my friend," replied the Physicist, "*Some* Scottish sheep are black."
At which point the Mathematician looked up from his paper and glanced out the window. After a few second's thought he said blandly: "In Scotland, there exists at least one field, in which there exists at least one sheep, at least one *side* of which is black."

Why did the chicken cross the Mobius strip?

A mathematician was taking an initiative test. He was asked to provide a solution to the following problem: "You are walking down a street and see a fire hydrant, with a hose lying on the ground nearby. The house opposite is on fire. What do you do?" The mathematician thought for a bit, and then said: "Well, clearly you plug the hose into the hydrant, turn on the water, and use it to put out the fire."

"Very good," said the interviewer. "Now imagine a similar situation, but the house is no longer on fire, and the hose is pluged into the fire hydrant." "But that's trivial," replied the mathematician, "you just unplug the hose and set fire to the house, then it's reduced to the previous problem."

Engineers try to link reality to equations, while Scientists try to link equations with reality.

Mathematicians refuse to accept that such links exist.

A Mathematician, a Biologist and a Physicist are sitting in a street cafe
watching people going in and out of the house on the other side of the street.
At a certain time they believe the house to be empty.
Then they see two people going into the house. Time passes.
After a while they notice three people coming out of the house...

The Physicist: "The measurement wasn't accurate."

The Biologist: "They must have reproduced."

The Mathematician: "Now if exactly 1 person enters the house then it will be empty again."

Any proof may be written in one line if you start sufficiently far to the left.

An engineer, a physicist, and a mathematician are shown a pasture containing a herd of sheep, and told to enclose them with smallest possible amount of fence. The engineer is first. He herds the sheep into a circle and then puts the fence around them, declaring, "A circle will use the least fence for a given area, so this is the best solution." The physicist is next. She creates a fence of infinite radius around the sheep, and then draws the fence tight around the herd, declaring, "This will give the shortest fence around the herd." The mathematician is last. After giving the problem a little thought, he puts a small fence around himself and then declares, "I define myself to be on the outside!"

Logic is the systematic method of coming to the wrong conclusion with confidence.

Four mathematicians and four biologists were travelling to a conference by train. The biologists stopped at the ticket office and bought four tickets for the outward journey. They were most surprised to see that the mathematicians only bough one ticket between them The biologists didn't say anything to the mathematicians (for fear of looking stupid) and the eight delegates got on the train. The biologists noticed the ticket inspector coming down the train and one whispered to another, "ah they're for it now". But the mathematicians calmly got up form their seats and squashed themselves into the toilet. The inspector (who was wise to people hiding in the toilet) knocked on the door. One of the mathematicians pushed their only ticket under the door. It was promptly stamped and returned, and the inspector continued on his way.

After two interesting conferences, the eight delegates met up at the station for the return journey. The biologists thought that they would take advantage of the trick the mathematicians had pulled on the way there, and only bough one ticket between them. They were completely perplexed when the mathematicians bought no tickets. The eight got on the train, and as the ticket inspector approached their carriage, the biologists piled into the toilet. There was a knock at the door, and they pushed their ticket underneath. They then heard the sound of muffled laughter as the mathematicians hurried away to the toilet at the other end of the carriage.