Ask HN: Any good math jokes?

54 points by whackedspinach ↗ HN
I'm trying to come up with a good math joke for our math team t-shirts. Last year we had "Know you limits, don't drink and derive." The shirt included a fuzzy graph.

I'm thinking about using an xkcd comic if the author gives me permission, but the images are somewhat small for t-shirts, so I might have to throw my own together anyways.

Got any good ideas?

138 comments

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Why did the chicken cross the Möbius strip?

To get to the same side.

This joke might be funnier if the answer is:

To get to the other side.

(The mathematicians will know that the chicken's quest will fail. Then they'll feel sorry for the chicken...)

But the non-mathematicians will JUST give you a weird look, rather than laughing and then giving you a weird look.
I don't know. A cliche can seem funny if you add a little twist, even if the twist is incomprehensible.
Why was 6 afraid of 7?

Because 7 8 9!

(7 ate 9)

I like how you explained it just in case.
I think you mean (ate 7 9). Don't feel bad, infix notation can creep up even on experienced Lisp programmers.
Those brackets were not for Lisp! God! They are also used for English.
I don't get it. Why did 7 eat 362,880?
If you do it in groups, you'd better be discrete.

(Related: Analysts do it continuously, and almost everywhere.)

Materials scientists do it with latex.

Biochemists do it with animals.

When civil engineers do it, the earth moves.

Software engineers do it all night long.

mathematicians do it in theory

(pretty old one)

Does that mean physicists do it in practice?
Mathematicians do it in groups, rings and fields.
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An engineer, a physicist, and a mathematician go to a conference together, and split a room in the hotel. They check in and go to sleep. The hotel is old (they couldn't afford anything better on professors' salaries), so the room is heated by a fireplace. A spark jumps out of the fire and catches the rug on fire. The engineer smells the smoke and wakes up. He jumps out of bed, sees the fire, and looks around. The first thing he sees is the ice bucket, so he takes it, fills it up from the sink, and throws the water on the fire. He drops the ice bucket next to the fireplace and goes back to bed.

The fire throws another spark, creating another fire. The physicist wakes up and sees the fire. He calculates that, given the size of the fire, and amount of oxygen needed to be displaced to put out a fire of said size, a glass of water will be sufficient. He fills up his water glass from the sink, and while running to the fire, throws the water at the fire at the exact distance from the fire that gets the water to the fire earliest, putting it out. He drops the glass next to the fireplace and goes to sleep.

The fire sparks once more, and the mathematician wakes up and sees the fire. He looks at the ice bucket and glass sitting next to the fireplace, says "Aha! A solution exists!", and goes back to bed.

It's a math joke, but not one suitable for t-shirts.

While we're at jokes not suitable for t-shirts:

A mathematician, an engineer and a physicist were travelling through Scotland when they saw a black sheep through the window of the train.

"Aha", says the engineer, "I see that Scottish sheep are black."

"Hmm", says the physician, "You mean that some Scottish sheep are black".

"Nonono", says the mathematician, "All we know is that there is at least one sheep in Scotland, and that at least one side of that one sheep is black."

What do you get when you cross an elephant and a banana?

(Elephant)(banana)sin(theta)

friend had a shirt that said

"be there or c squared minus a squared"

lol

Surprised this isn't already here, pretty popular at my college:

I wish I was your derivative, so I could lie tangent to your curves.

And the companion bio-joke:

I wish I was mRNA polymerase, so I could unzip your genes.

Wow, best pickup line I've ever heard :-)
I've never heard them called "mRNA polymerases." RNA polymerase should do just fine.

In fact, wouldn't helicase do better?

Helicase is what unzips the genes, not RNA polymerase. RNA polymerase allows transcription (or creation of an mRNA molecule complementary to the given gene) to take place.
That one is so bad, because it doesn't work. Presumably the derivative is used to calculate a tangent line. However, a tangent line touches the curve only at one point, unless the curve is totally flat. Either way, this is not what you want. You want fuckin' Taylor series approximations. (They won't work on curves that aren't smooth, but that's all right, because those are the curves you want to touch anyway.)

Aww yeah.

Strictly speaking, the Taylor series won't even do what you're wanting them to do for smooth functions. (Consider the function e^{-1/x^2}, whose Taylor series is zero at the origin. In fact, given any sequence of numbers, you can cook up a smooth function which has that sequence as the coefficients of its Taylor series at zero.) If you want the Taylor series to agree with the function in an entire neighborhood of a point, you want the function to be real (or complex) analytic (at least in a neighborhood of that point).
That's true. I was careful to say "They won't work on curves that aren't smooth", which doesn't mean "They will work on all curves that are smooth", so I think what I said is still correct.

And as long as we are going for perfect rigor, the function you describe is undefined at x=0; you have to make it piecewise and say "if x=0, then this function is 0". (And I could say something about "you want natural curves, not this artificial pieced-together stuff.")

Also, I believe the Taylor series for that function is well-defined and accurate at all points other than x=0, so you can just pick one of those points. Are there smooth functions whose Taylor series are wrong everywhere? I doubt it. And one might argue that it's pretty problematic that, e.g., with the function "0 if x≤0, e^{-1/x^2} if x>0", a Taylor series at any positive point will be wrong for all negative numbers, and a Taylor series at any nonnegative point will be wrong for all positive numbers... well, I dunno, touching half of the entire range of a curve is still a lot (an infinite amount, in fact).

One could imagine a bunch of functions pieced together to make a smooth function (e.g. "e^{-1/x^2} * e^{-1/(x-1)^2} for 0<x<1, e^{-1/(x-1)^2} * e^{-1/(x-2)^2} for 1<x<2, ...") whose Taylor series are all accurate only over a small, finite domain. I guess that kinda answers my question. But at this point I would apply the "natural curves" objection. I wonder, are there smooth non-piecewise functions whose Taylor series are all wrong like that? (Absolute value is a piecewise function, so I'd probably reject anything with absolute value.)

There's always the classic, 'Snakes ⊂ ℝ²'.
Can someone explain this one?
ℝ² is the Cartesian plane; it is a reference to the movie "Snakes On A Plane".
i 8 √-1 Πs. (I ate imaginary pies?) You might have to play around with it, but I hope it's a good start. :)
There are two hard problems in computer science. Naming, cache invalidation, and off-by-one errors.
Make that 10 hard problems.

Similar to - There are 10 kinds on people. Those who understand binary and those who don't.

My favorite take on that one is more for compiler and embedded folks:

There are 1 kinds of people in this world. Those who know how to save bits. The rest are the default case.

xkcd comics are already licensed under a Creative Commons Attribution-Noncommercial 2.5 license. That's probably all you need for a math team t-shirt.
upvoted it (at this time, it cancelled out a downvote).

No idea why it was initially downvoted, it's good information to point out. So long as you don't make money off the shirts, it's ok to use xkcd comics.

I saw that, but in the end some of the images are only about 700x400 px. At 200 ppi (which is what t shirts should be printed at, I guess), that just isn't a high enough resolution. And I'm not sure If I really want to make it larger since it will not look all that good.
You could always try contacting Randall and explain what you'd like to use the particular strip for to see if you could get a larger image.

Even if the current size was large enough, he would probably appreciate knowing about his work being printed like that as most people do.

You could load an xkcd comic into Inkscape or another vector graphics editor and trace it out by hand. It wouldn't take that long, and the end result would be a vector graphic that you could render to whatever size or resolution you need. (Creating a derivative work like this is allowed by the license.)
What is the par value of a zero-coupon bond with no maturity?

Pee dollars!

Did you see the SNL segment on options? It was put-call parody!

Complex analysis: it's as easy as pulling out an i.

Analysis, something, something. Balls! (I haven't quite finished that one).

Math team: like being star quarterback, except you have to wait ten years before you can order the football team around.
"Leibnitz > Newton" could provoke a fist fight. This would be hilarious to see.

edit: Better than xkcd, depending on your sense of humor (i.e., whether you have one) is smbc-comics.com. Dunno how he licenses his stuff though.

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Physicist, pastor and mathematician on the top of a skyscraper. They are asked to jump precisely into the swimming pool on the ground. Phsycist calculates wind, distance, perspective, jumps and lands in the pool. Pastor meditates, prays, focuses, jumps and lands in the pool. Mathematician calculates a beautiful parabel, jumps and goes straight up to the sky. What happend? Oh well, he made a sign flaw :)
A sahillavingia original:

Q: What did the difficult cartesian-coordinate system tell his problem-solver when he wanted to visit Antartica?

A: You should go polar!

here's one from the last decade.

Q. what did the math teacher say when she saw tennis star monica seles?

A. isosceles

   Math Club
then put a picture of a hot chick, and some MDMA

then Transcendental Numbers

Q: what did the zero say to the eight? A: nice belt!
An all time favorite of mine! (:
An infinite number of mathematicians walk into a bar. The first one orders a beer. The second orders half a beer. The third, a quarter of a beer. The bartender says "You're all idiots", and pours two beers.

more: http://www.metafilter.com/76377/Two-mathematicians-walk-into...

Or its sibling: a genie grants both a mathematician and an engineer their greatest desire to be located at the end of the room given that each step they take towards it is half the distance than their last. The mathematician throws his arms up and yells "Impossible! I'll never reach it," and storms out of the room. The engineer just smiles and says to the genie, "I can get close enough."
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So all but one have to share a glass? Seems unpractical.
They possibly have an infinite amount of time to share the glass around
Similar:

An infinite number of mathematicins walk into a bar. The first one orders a beer. The second orders half a beer. The third, a third of a beer. The bartender says, "what do you think I am, an idiot?" and kicks them all out.

An infinite number of mathematicians walk into a bar. The first one orders a beer. The second orders two beers. The third, three beers. The bartender says, "you guys owe me a twelfth of a beer."

(Explanation of that last one: http://en.wikipedia.org/wiki/1%2B2%2B3%2B4%2B... )

Q: What the integral of (1/cabin)dCabin?

A: Beach Hut

(Log Cabin + C)

[Maybe just the formula would fit on a T Shirt, and you get to explain it to people who ask?]

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Q: Integral dCabin/Cabin?

A: natural log cabin

I love the people in this thread giving jokes that are aimed at five year olds, rather than a math team who's previous joke was "don't drive and derive".
whats a chefs favorite triangle? isauceles

how did the abelian group get to work? it commuted

why do addition and the integers carpool? because theyre a commutative group