Do good math jokes exist?

The sad thing about math jokes is that they quickly get old.

You’ve heard the more generic ones, of course. Past a point you wonder: this all you got? Really?

MathOverflow, luckily, has a good repository of jokes. Here’s some:

“Let ε < 0.”

“Show that 17 x 17 = 289. Generalize this result.”

“Why did the chicken cross the Mobius band?”

“Take a positive integer N. No wait, N is too big; take a positive integer k.”

Your momma’s so fat she’s not embeddable in R^3. Oh yeah? Your momma’s so fat she contradicts Whitney’s theorem.

A topologist is someone who doesn’t know the difference between his ass and a hole in the ground but does know the difference between his ass and two holes in the ground.

I went to visit him while he was lying ill at the hospital. I had come in taxi cab number 14 and remarked that it was a rather dull number. “No” he replied, “it is a very interesting number. It’s the smallest number expressible as the product of 7 and 2 in two different ways.”

A comathematician is a device for turning cotheorems into ffee.

A coconut is just a nut.

Old Macdonald had a form; ei /\ ei = 0.

What shape of pasta takes the least time to eat? Brachistochroni!

You might be a mathematician if you think fog is a composition.

The Yoda embedding, contravariant it is.

recursive: (λ damn. damn (damn)) (λ damn. damn (damn))

Q: What do you get when you cross a chicken with an elephant?

A: The trivial elephant bundle on a chicken.

Prof: “Give an example of a vector space.” Student: “V.”

“What’s an anagram of Banach-Tarski?” “Banach-Tarski Banach-Tarski.”

“What’s the value of a contour integral around Western Europe?” “Zero. All the Poles are in Eastern Europe.”

Why did the mathematician name his dog “Cauchy”? Because he left a residue at every pole.

Physicist: “What kind of math do you do?” Mathematician: “Knot theory.” Physicist: “Me neither!”

The spectral sequence is like the mini-skirt; it shows what is interesting while hiding the essential.

Q: What is non-orientable and lives in the ocean?

A: Möbius Dick.

“The number you have dialed is imaginary. Please, rotate your phone by 90 degrees and try again.”

(A comment about a paper) 3 lines before section 2.1: A few typos: corresponds, 5-isogeny (I guess a 5-isogenie grants you five wishes?)

Theorem: There are infinitely many composite numbers.

Proof: Suppose there are only finitely many, and multiply them together.

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

A: One: she gives it to three physicists, thus reducing it to a problem that has already been solved.

Q: What kind of maps should you take with you on car trips?

A: Automorphisms.

After introducing general topological spaces, the professor began to introduce the notion of convergence without a metric. He turned around and said, “I have no balls.”

Perhaps the question should be, not “Do good math jokes exist“, but “are they unique“?

Do good math jokes exist? Under the axiom of choice, sure. But it’s not possible to find an explicit example.

It was proven by Cantor that a good math joke exists. Unfortunately, his proof was entirely non-constructive.

*    *    *    *    *    *

Here are some of the longer ones:

e^x was walking down the street one day and met a polynomial running in the opposite direction.

“Wait, why are you running?”

“There’s a differential operator over there! It could differentiate me and turn me into zero!”

And the polynomial continued running in fright.

Ha ha,” e^x said to himself. “I’m e^x! Let them differentiate me as many times as they want, it makes no difference to me!”

So ex walked on and reached the differential operator. He confidently introduced himself: “Hi, I’m e^x!”

The reply: Hi, I’m ∂/∂y!”


A poet, a priest, and a mathematician are discussing whether it’s better to have a wife or a mistress.

The poet argues that it’s better to have a mistress because love should be free and spontaneous.

The priest argues that it’s better to have a wife because love should be sanctified by God.

The mathematician says, “I think it’s better to have both. That way, when each of them thinks you’re with the other, you can do some mathematics.”


A mathematican walks into a bar accompanied by a dog and a cow. The bartender says, “Hey, no animals are allowed in here!” The mathematician replies, “These are very special animals.” “How so?” “They’re knot theorists.” The bartender raises his eyebrows and says, “I’ve met a number of knot theorists who I thought were animals, but never an animal that was a knot theorist.” “Well, I’ll prove it to you. Ask them them anything you like.” So the bartender asks the dog, “Name a knot invariant.” “Arf! Arf!” barks the dog. The bartender scowls and turns to the cow asking, “Name a topological invariant.” “Mu! Mu!” says the cow. At this point the bartender turns to the mathematican and says, “Very funny.” With that, he throws the three out of the bar. Outside, sitting on the curb, the dog turns to the mathematican and asks, “Do you think I should have said the Jones polynomial instead?”


There’s a mathematician whose non-mathematician friends are constantly ribbing him because his field is just so abstract and seems to have no relevance to the real world. One day, it gets to him, and he resolves to arm himself with some practical applications of research mathematics for the next encounter. He realizes that his own specialty (mathematical logic) is probably too far beyond them to be of any use there, so he goes to the department bulletin board to find an upcoming talk about something practical. Luckily, a talk is scheduled that afternoon on “the theory of gears.” “Perfect!” he says. Nothing could be more practical, more down-to-earth. That afternoon, he’s so excited that he goes to the talk five minutes early and sits in the first row of seats. Then, at the scheduled time, the speaker stands up and begins: “While the theory of gears with real numbers of teeth is well understood….


Hilbert had a student who one day presented him with a paper purporting to prove the Riemann Hypothesis. Hilbert studied the paper carefully and was really impressed by depth of the argument; but unfortunately he found an error in it which even he could not eliminate. The following year the student died. Hilbert asked the grieving parents if he might be permitted to make a funeral oration. While the student’s relatives and friends were weeping beside the grave in the rain, Hilbert came forward. He began by saying what a tragedy it was that such a gifted young man had died before he had had an opportunity to show what he could accomplish. But, he continued, in spite of the fact that this young man’s proof of the Riemann Hypothesis contained an error, it was still possible that some day a proof of the famous problem would be obtained along the lines which the deceased had indicated. “In fact,” he continued with enthusiasm, standing there in the rain by the dead student’s grave, “let us consider a function of a complex variable….


(the following four relate to “contributions to the mathematical theory of big game hunting”)

The Hilbert, or axiomatic, method. We place a locked cage at a given point of the desert. We then introduce the following logical system.

  • Axiom I. The class of lions in the Sahara Desert is non-void.
  • Axiom II. If there is a lion in the Sahara Desert, there is a lion in the cage.
  • Rule of Procedure. If p is a theorem, and “p implies q” is a theorem, then q is a theorem.
  • Theorem I. There is a lion in the cage.

The method of inversive geometry. We place a spherical cage in the desert, enter it, and lock it. We perform an inversion with respect to the cage. The lion is then in the interior of the cage, and we are outside.

The method of projective geometry. Without loss of generality, we may regard the Sahara Desert as a plane. Project the plane into a line, and then project the line into an interior point of the cage. The lion is projected into the same point.

The Bolzano-Weierstrass method. Bisect the desert by a line running N-S. The lion is either in the E portion or in the W portion; let us suppose him to be in the W portion. Bisect this portion by a line running E-W. The lion is either in the N portion or in the S portion; let us suppose him to be in the N portion. We continue this process indefinitely, constructing a sufficiently strong fence about the chosen portion at each step. The diameter of the chosen portions approaches zero, so that the lion is ultimately surrounded by a fence of arbitrarily small perimeter.


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