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# Mathematical jokes

There are many thousands of **mathematical jokes** available (e.g. see some of the references for the jokes listed below), and there are often several variations of any particular joke. Some jokes do not need any mathematical knowledge to appreciate, especially those based on stereotypes of mathematicians and other professions. Some jokes are based on double meanings, where a word has different meanings in common usage and in mathematics. Some jokes do require a little mathematical knowledge to understand.

## Contents |

## Stereotypes

*Regarding sheep*^{[1]}

- 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."

*Reality 1*^{[2]}

- An engineer thinks that equations are an approximation to reality.
- A physicist thinks reality is an approximation to equations.
- A mathematician doesn't care.

*Reality 2*^{[3]}

- Engineers try to link reality to equations, while Scientists try to link equations with reality.
- Mathematicians refuse to accept that such links exist.

## Double meanings

*Noah's Ark* from George Gamow, Matter, Earth, and Sky, 1965.^{[4]}

- At this point the author cannot resist telling a story of what happened when Noah's Ark, loaded with animal couples of all species, finally landed at Mt. Ararat. As a lion and a lioness, a deer and a doe, a rooster and a hen, etc., were coming onto solid land, Noah was giving them instructions to spread out and to multiply.

- Next spring, walking around the land which was again flourishing after the Great Deluge waters receded, Noah was enjoying the sight of little lion cubs, yearlings, baby chickens, etc., running around. But then he found a couple of snakes that had no offspring.
- "Didn't I tell you to multiply?" asked Noah in anger. "Why didn't you?"
- "Sorry, Sir," answered the snakes, "we can't multiply because we're adders."

- A year passed, and Noah, walking around his property, found under a big table (built for the family's outdoor meals) the same two snakes — surrounded by a dozen or so newly-born offspring.
- "You told me last year," said Noah in surprise, "that you couldn't multiply because you're adders. How is it that you managed to multiply?"
- "Oh, sir," said the papa adder proudly, "you see, we've found a log table!"

- Let us hope that this story will persuade those students who do not know how to use the log table to learn this art.

- Notes:
- earliest reported version is dated 1938
- the first version to mention a log table is dated 1947

## Mock mathematics

*A proof that 2 = 1*

let a = b a×a = a×b .. multiply both sides by a a×a − b×b = a×b − b×b .. subtract b×b from both sides (a+b)×(a−b) = b×(a−b) .. factorise (a+b) = b .. cancel (a−b) from both sides b+b = b .. substitute a = b 2×b = b .. simplify 2 = 1 .. divide both sides by b

## Some maths knowledge helps

There are 10 kinds of people in this world: those who understand binary, and those who don't.

- Note: in binary 10
_{2}represents decimal 2_{10}.