ProofWiki:Jokes

0.999...=1

Q: How many mathematicians does it take to change a lightbulb?

A: 0.999999 ...

Banach-Tarski Paradox

Q: Give me an anagram of Banach-Tarski.

A: Banach-Tarski Banach-Tarski.

Educational Standards

Two captains of industry, Arthur and George, were in a restaurant discussing the state of educational standards, particularly in the field of mathematics. Arthur was convinced they were slipping badly, and that your average college student was completely mathematically illiterate. George, on the other hand, was confident that any student would at least know the basics of calculus.

"I bet you a hundred bucks," said Arthur, "that if you were to ask a random college student a basic question in calculus, he wouldn't understand the question, let alone furnish you with an answer."

"I'll think about that," said George. "Not sure whether to take you up on your bet or not, but I reckon you'd be wrong."

Arthur slipped off to the mens' room at that point, and while he was gone, George called over the waitress Jody. (He knew that was her name because it was written on a badge pinned to her uniform. This appears to be a custom in certain chain diners.)

"I'd like you to help settle a wager between me and my colleague," he said. "When he comes back, I'm going to call you over, and ask you a question, to which you are to answer: one third x cubed."

"Wuntur dex cue?"

"One third x cubed."

"One thurrd ex cuebd."

"That's it, one third x cubed."

"One third ... x cubed."

"That's it, perfect. There's a good tip in it for you."

Arthur returned. George said, "Yes, I think I will take you up on it. A hundred bucks says our waitress can answer such a question. Hey, Jody! What's the indefinite integral of x squared with respect to x?"

"One third x cubed," replied Jody, dutifully.

"You see?" said George, pocketing Arthur's hundred.

As Jody turned away, she called back over her shoulder, "Plus a constant."

George ruefully took Arthur's hundred back out of his pocket and dropped it onto the table.

Knot Theory

Student A: "What's your favourite area of mathematics?"

Student B: "Knot theory."

Student A: "Me neither."

• Colin C. Adams: The Knot Book (1994): Knot Jokes and Pastimes (attributed to Martin Scharlemann)

Natural Numbers

Q: "Why do computer scientists have nine fingers?"

A: "Zero, one, two, three, four; five, six, seven, eight, nine."

Circle Geometry

The roundest knight at King Arthur's round table was Sir Cumference.

He acquired his shape from too much pi.

Sufficiently Large

$1+1 = 3$, for sufficiently large values of $1$.

Why? Because $1.4 + 1.4 = 2.8$.

The result follows after rounding to the nearest integer.

Number Bases

Why do mathematicians get Halloween and Christmas confused?

Because $\mathsf{Dec} \ 25$ equals $\mathsf{Oct} \ 31$.

• Ian Stewart: Professor Stewart's Hoard of Mathematical Treasures (2009): Halloween $=$ Christmas (but it's a considerably older joke than that.)

Computer Prayer

Our Program which art in Memory,

"Hello World!" be Thy Name.

Thy Operating System come, Thy Commands be done,

at the Printer as it is on the Screen.

Give us this day our Data Dump,

and forgive us our I/O Errors

as we backup those whose Files are faulty.

Lead us not into frustration, and deliver us from email

for Thine is the Algorithm, the Application, and the Solution,

looping forever and ever.

Return.

Average Number of Hands

Most people in the world have more than the average number of hands.

Six

	\(\displaystyle \)	\(\displaystyle \)	\(\)	\(\displaystyle \frac {\sin x} {\mathrm n}\)	\(\displaystyle \)
	\(\displaystyle \)	\(\displaystyle \)	\(=\)	\(\displaystyle \mathrm {si} \ x \frac{\mathrm n}{\mathrm n}\)	\(\displaystyle \)
	\(\displaystyle \)	\(\displaystyle \)	\(=\)	\(\displaystyle 6\)	\(\displaystyle \)

Computer Encoding

Link to a ROT26 encoder:

http://www.rot26.org/

All Odd Numbers Are Prime

Proof by inductive argument:

$1$, that's prime (well not technically, but that's just mathematical double-talk).

$3$, that's prime.

$5$, that's prime.

$7$, that's prime.

$9$, that's prime (although when I measured it, it looked like it might not be - experimental error, ignore that one)

$11$, that's prime.

$13$, that's prime.

We can extrapolate from there.

Logarithms

Hear about the constipated mathematician?

He worked out logs with a pencil.