The Mathematician’s Answer is a meta-joke about how mathematicians usually behave in jokes. From tvtropes:

If you ask someone a question, and he gives you an entirely accurate answer that is of no practical use whatsoever, he has just given you a Mathematician’s Answer.

It goes further on to say: “A common form of giving a Mathematician’s Answer is to fully evaluate the logic of the question and give a logically correct answer. Such a response may prove confusing for someone who interpreted what they said colloquially.”

Perhaps the most famous example is the hot-air balloon joke, where a man in a hot-air balloon asks someone where he is, to which the response is, “You’re in a hot-air balloon!” The rider concludes that the responder must be a mathematician, because the answer given was absolutely correct but utterly useless.

The tvtropes site contains a bunch of examples of Mathematician’s Answer in dialog. But this kind of joke also sometimes pokes fun at actions as well as words. My favorite is the hotel joke (this version from the Cherkaev “Math Jokes” collection):

An engineer, a physicist and a mathematician are staying in a hotel.

The engineer wakes up and smells smoke. He goes out into the hallway and sees a fire, so he fills a trash can from his room with water and douses the fire. He goes back to bed.

Later, the physicist wakes up and smells smoke. He opens his door and sees a fire in the hallway. He walks down the hall to a fire hose and after calculating the flame velocity, distance, water pressure, trajectory, etc. extinguishes the fire with the minimum amount of water and energy needed.

Later, the mathematician wakes up and smells smoke. He goes to the hall, sees the fire and then the fire hose. He thinks for a moment and then exclaims, “Ah, a solution exists!” and then goes back to bed.

In line with the engineer/physicist/mathematician trio, another great one is the Scottish sheep joke:

A mathematician, a physicist, and an engineer were traveling 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 physicist, “You mean that some Scottish sheep are black.”

“No,” 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!”

And then, we have the infamous examples where it was the students ironically who used the Mathematician’s Answer on their math teachers:

Now, aside from the meta-joke status of the Mathematician’s Answer, is there any truth to it? Do math-minded people really say, “You’re in a hot air balloon,” in real life?

From all the math classes I’ve taken at college, I have never witnessed a professor respond unwittingly with a Mathematician’s Answer. Every time it was used, it was clear that it was meant as a joke. Sure, some live up to mathematician archetype, but they’re all normal people, not John Nashes.

In high school, my favorite form of humor was the pun. Starting junior or senior year of college, however, I had somehow transitioned to the Mathematician’s Answer as my go-to response when I can’t think of anything to say. It is extremely easy to use, as almost every situation can lead to this kind of joke. It’s really fun to use and really versatile.

It doesn’t even need to be used in response to a question. Just yesterday, someone remarked that it was March 1st already. Immediately, I added, “Oh yeah, that’s exactly one month away from April 1st.” The same person later asked how far 10 yards was, and, like a true mathematician, I answered by saying it was like 5 yards but double that.

Our campus Internet has one network called “RedRover” and another called “RedRover-Secure.” Someone asked what the difference between these was, and I quickly responded, “Well, they’re the same, except one of them is secure.”

I think it interests me because I’m generally fond of logical and tautological humor. The only downside of the Mathematician’s Answer is that it doesn’t really work in anything that is related to mathematics. The language of math is designed to minimize ambiguity, and even when situations do arise where there are two interpretations, it’s much harder to distinguish between a literal and a figurative meaning. One of the few mathematical ambiguities I know if is if someone writes

,

do we choose x and y such that x is at least 1 and y is at most 10, or is it that both x and y are between 1 and 10? On the other hand, Mathematician’s Answer works really well in areas as far removed from mathematics as possible. Anyway, here is one last example:

An engineer, a physicist and a mathematician find themselves in an anecdote, indeed an anecdote quite similar to many that you have no doubt already heard. After some observations and rough calculations the engineer realizes the situation and starts laughing. A few minutes later the physicist understands too and chuckles to himself happily as he now has enough experimental evidence to publish a paper.

This leaves the mathematician somewhat perplexed, as he had observed right away that he was the subject of an anecdote, and deduced quite rapidly the presence of humor from similar anecdotes, but considers this anecdote to be too trivial a corollary to be significant, let alone funny.