Mathematical joke
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A mathematical joke is a form of humor which relies on aspects of mathematics or a stereotype of mathematicians to derive humor. The humor may come from a pun, or from a double meaning of a mathematical term. It may also come from a lay person's misunderstanding of a mathematical concept (which is not wholly unexpected). These jokes are frequently inaccessible to those without a mathematical bent.
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[edit] Pun-based jokes
An example:
- Why do mathematicians like national parks?
- Because of the natural logs.
A more sophisticated example:
- Person 1: What's the integral of 1/cabin?
- Person 2: Log cabin.
- Person 1: No, a houseboat - you forgot to add the c!
The first part of this joke relies on the fact that the primitive (formed when finding the antiderivative) of the function 1/x is log(x). The second part is then based on the fact that the antiderivative is actually a class of functions, requiring the inclusion of a constant of integration, usually denoted as C - something which many calculus students forget. Thus, the indefinite integral of 1/cabin is "log(cabin) + c", or "A log cabin plus the sea", ie. "A houseboat".
Yet another example is:
- Q: What do you get if you cross an elephant with a chicken?
- A: Chicken elephant sine theta.
This relies on the formula for the "cross product" of two vectors X and Y being equal to Y times X multiplied by the sine of the angle between them (theta being the usual name for an arbitrary angle, similar to the names X and Y for numbers).
A followup to the above joke is:
- Q: What do you get if you cross a mosquito with a mountain climber?
- A: Trick question! You can't cross a vector with a scalar!
This joke relies on two puns: one on the word "vector", meaning either a member of a vector space or a carrier of an infectious agent (i.e., the mosquito), and the other on the word "scalar" (i.e., a quantity which is not a vector), versus "scaler" (i.e. one who climbs).
[edit] 'Mathematical pun'-based jokes
- There are only 10 types of people in the world -- those who understand binary, and those who don't.
This joke relies on the fact that mathematical expressions, just as expressions in natural languages, may have multiple meanings. When multiple meanings are available, puns are possible. In this case a pun is made using the expression 10. For non-mathematicians or non-computer programmers 10 almost always refers to the number ten. However, in binary, the expression 10 means the number two. Thus the joke says that there are only two kinds of people, those who understand binary, and those who don't. However, those who do not understand binary will certainly not get the joke. This joke is only feasible in written form; when speaking a binary number aloud, most would phrase "10" as "One Zero" rather than "Ten".
A self-deprecating version is as follows:
- There are only 10 types of people in the world -- those who understand binary, and those who get laid.
The following joke refers to the original joke:
- There are only 10 types of people in the world -- those who understand trinary, those who don't, and those who mistake it for binary.
A similar joke may be played by asking the question:
- If only DEAD people understand hexadecimal, how many people understand hexadecimal?
In this case, DEAD refers to a hexadecimal number (57005), not the state of being no longer alive.
Another pun using different radices, sometimes attributed to computer scientists, asks:
(This one is also often attributed to computer scientists: Real programmers confuse Halloween and Christmas -- because dec(25)=oct(31).)
Another joke involving counting is:
- There are three kinds of people in the world: those who can count, and those who can't.
This implies, of course, that the person making the statement is the second kind.
Almost everyone knows the trite line: "Why did the chicken cross the road?" "To get to the other side". A mathematical variation follows as: "Why did the chicken cross the Möbius strip?" This joke relies on the audience knowing that since the Möbius Strip is a surface with only one "side" (i.e. one "edge"), anyone trying to give the typical answer will realise its impossibility. The answer is sometimes also given as "To get to the same side", with the same rationale.
"Did you just grab my asymptote?!" is another example of a mathematical pun.
- I love f(x)ou.
This pun is based on that fact that the function f(x) is the same as the letter y in terms of graphical equations. The possibilities for other puns similar to this are many, though the above is the simplest to understand.
A pun based on logaritms:
- After the great flood Noah gathered all the animals on the beach and told them "We've all survived the perils of the flood, now you must go forth and multiply." A small snake replied with a sad voice "I can't multiply, I'm an adder." Noah thought for a while, then he went into the forrest with an axe and cut down some trees. He brought them to the beach and constructed a small wooden table. Then he told the adder: "Now you will be able to multiply even though you're an adder. I've built you a log table!"
The first part of the pun is the dual meaning of the word adder and the final punch line is a reference to Logarithm tables
[edit] Mathematical reasoning
A similar set of equivocal jokes applies mathematical reasoning to situations where it is not entirely valid. Many of these are based on a combination of well-known quotes and basic logical constructs such as syllogisms:
Examples:
- Premise I: Power corrupts.
Premise II: Knowledge is power.
Conclusion: Therefore, knowledge corrupts.
- Premise I: God is love.
Premise II: Love is blind.
Premise III: Stevie Wonder is blind.
Conclusion: Therefore, Stevie Wonder is God.
The second syllogism happens to be a logical fallacy even when taken in a purely logical sense.
There are also a number of joke proofs, such as the proof that "Girls are evil":
- "Girls require time and money":
- "Time is money":
- So girls are money squared:
- "Money is the root of all evil":
- So girls are evil:
Some might think that the square root of a number squared is equal to its absolute value (actually, in the above formula it is the square of the number's root, so this assumption is false), thus girls are actually equal to 
. Given that evil is considered a negative quality, one may argue that this proof only exemplifies that girls are in fact, good, so the argument goes. Alternatively, to say that girls are equal to the absolute value of evil may imply that they are absolutely evil. In fact, this case is the square of a square root and not the square root of a square. The 
, i.e. a negative evil, would actually be 
, which squared would still be 
. Positive or negative evil, rooted and squared, is still positive or negative respectively.
Another set of jokes relate to the absence of mathematical reasoning, or misinterpretation of conventional notation:
Examples:
(That is, the limit as x goes to 8 is a sideways 8 or the infinity sign, in the same way that the limit as x goes to three is a sideways 3 or the Greek letter omega.)
(The n’s cancel leaving the word six divided by one.)
- P = NP, if N = 1 or P = 0.
(The joke plays on the NP conjecture, one of the more important open problems in mathematics. In the conjecture, neither N nor P represent real numbers.)
[edit] Mathematicians
Some jokes are based on stereotypes of mathematicians tending to think in complicated, abstract terms, causing them to lose touch with the "real world".
Many of these jokes compare mathematicians to other professions, typically physicists, engineers, or the "soft" sciences in a form similar to those which begin "An Englishman, a Scotsman and an Irishman ..." or the like. The joke generally shows the other scientist doing something practical, while the mathematician does something less useful such as making the necessary calculation but not performing the implied action.
Examples:
- A mathematician and his best friend, an engineer, attend a public lecture on geometry in thirteen-dimensional space. "How did you like it?" the mathematician wants to know after the talk. "My head's spinning", the engineer confesses. "How can you develop any intuition for thirteen-dimensional space?" "Well, it's not even difficult. All I do is visualize the situation in n-dimensional space and then set n = 13."
- A mathematician, a biologist and a physicist are sitting in a street café watching people going in and coming out of the house on the other side of the street. First they see two people going into the house. Time passes. After a while they notice three persons coming out of the house. The physicist says, "The measurement wasn't accurate." The biologist says, "They must have reproduced." The mathematician says, "If one more person enters the house then it will be empty."
- A mathematician and an engineer agreed to take part in a psychological test. They sat on one side of a room and waited not knowing what to expect. A door opened on the other side and a naked woman came in the room and stood on the far side. They were then instructed that every time they heard a beep they could move half the remaining distance to the woman. They heard a beep and the engineer jumped up and moved halfway across the room while the mathematician continued to sit, looking disgusted and bored. When the mathematician didn't move after the second beep he was asked why. "Because I know I will never reach the woman." The engineer was asked why he chose to move and replied, "Because I know that very soon I will be close enough for all practical purposes!" (The joke hints at the dichotomy paradox.)
An example of a joke relying on mathematicians' propensity for not taking the implied action is as follows:
- A mathematician, an engineer and a chemist are at a conference. They are staying in adjoining rooms. One evening they are downstairs in the bar. The mathematician goes to bed first. The chemist goes next, followed a minute or two later by the engineer. The chemist notices that in the corridor outside their rooms a rubbish bin is ablaze. There is a bucket of water nearby. The chemist starts concocting a means of generating carbon dioxide in order to create a makeshift extinguisher but before he can do so the engineer arrives, dumps the water on the fire and puts it out. The next morning the chemist and engineer tell the mathematician about the fire. He admits he saw it. They ask him why the hell he didn't put it out. He replies contemptuously "there was a fire and a bucket of water: it summed to zero, obviously."
Mathematicians are also averse to making sweeping generalizations from a small amount of data, preferring instead to state only that which can be logically deduced from the given information - even if some form of generalization seems plausible:
- 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 at least one Scottish sheep is black."
- "No," says the mathematician, "all we know is that there is at least one sheep in Scotland, at least one side of which looks black from here!"
A variant has the punchline "No," says the mathematician, "all we can say is that there is at least half of a black sheep in Scotland."
Pure mathematicians are mainly concerned with the properties of the abstract systems under study, not their actual applications. However, such applications are sometimes found in mathematics itself, resulting in new insights as old problems are cast in new light. In striving not to miss such connections, mathematicians often see problems in novel (but theoretically valid) ways, which unfortunately are not always as illuminating as one could wish for:
- A sociologist, a physicist and a mathematician are all given equal amounts of fencing, and are asked to enclose the greatest area. The sociologist pauses for a moment and decides to enclose a square area with his fence. The physicist, realizing he can fence off a greater amount of land with the same amount of fencing, promptly sets his fence in the form of a circle, and smiles. "I'd like to see you beat that!" he says to the mathematician. The mathematician, in response, takes a very small piece of his own fencing, and wraps it around himself, proclaiming, "I define my location to be outside of the fence!"
A small set of jokes involves only mathematicians, such as the following involving statisticians:
- Three statisticians go duck hunting. Their dog chases out a duck and it starts to fly. The first statistician aims and takes his shot, it misses a foot too high. The second statistician aims and takes his shot, it misses a foot too low. The third statistician says, "We got him!"
The humor there is derived from the fact that the average of the shots hits the duck, and so it is dead.
Another type of joke pokes fun of historical mathematicians. For instance:
- Why did the chicken cross the road?
- Pierre de Fermat: Because the margin on its side was too small.
[edit] Non-mathematicians
The next category of jokes comprises those that exploit common misunderstandings of mathematics, or the expectation that most people have only a basic mathematical education, if any.
Examples:
- A visitor to the Royal Tyrell Museum was admiring a Tyrannosaurus fossil, and asked a nearby museum employee how old it was.
- "That skeleton's sixty-five million and three years, two months and eighteen days old," the employee replied.
- "How can you know it that well?"
- "Well, when I started working here, I asked a scientist the exact same question, and he said it was sixty-five million years old - and that was three years, two months and eighteen days ago."
In the above example, the humour is that the employee fails to understand the precision of the age of the fossil. (However, this is not strictly a joke about mathematics, but instead about science/engineering.)
- Two mathematicians are in a bar. The first one says to the second that the average person knows very little about basic math. The second one disagrees, and claims that most people can cope with a reasonable amount of math. The first mathematician goes off to the washroom, and in his absence the second calls over the waitress. He tells her that in a few minutes, after his friend has returned, he will call her over and ask her a question; all she has to do is answer, "One third x cubed." She agrees, and goes off mumbling to herself. The first guy returns and the second proposes a bet to prove his point. He says he will ask the blonde waitress an integral, and the first laughingly agrees. The second man calls over the waitress and asks, "What is the integral of x squared?" The waitress says, "One third x cubed." Then, while walking away, she turns back and says, "Plus a constant!"
In the above example, the humour is that the waitress, chosen as an example of someone not expected to know much mathematics beyond adding up the bill, turns out to know enough calculus to correct the mathematician's omission.
[edit] Non-mathematical mathematical jokes
One final form of mathematical humor comes from using mathematical tools (both abstract symbols and physical objects such as calculators) in various ways which transgress their intended ambit. These constructions are generally devoid of any "real" mathematics, besides some basic arithmetic. One of them is using mathematical formalism to spell out words and phrases in the form of a rebus, often of a crude nature. Another is calculator spelling; words and phrases formed by entering a number and turning the calculator upside down. Due to their crudeness and relative simplicity (requiring only basic calculator skills to achieve), these are usually spread by schoolchildren. Often the words are accompanied by stories involving numbers that lead to the "final solution".
[edit] Examples of mathematical rebuses
[edit] Rebus No: 1.
This can be read, interpreting the expression mathematically, as "Before I root you, are you over 18?" (in Australian and New Zealand English, "to root" is slang for "to have sex with", from the verb "rut", meaning animal mating).
[edit] Rebus No: 2.
A t-shirt from the University of Chicago reads: 
or: The limit of sex (the integral looks like an "S") as U (you) approaches U of C is zero, implying that the average U of C student is unlikely to engage in sexual relations.
[edit] Rebus No: 3.
- A hillbilly asks his son what he learned in school that day. The son responds, "Pi R squared" (
). The angry father comes back with, "What are they teachin' you in that place? Everybody knows cornbread are squared; pie are round!"
[edit] Other Jokes
[edit] Math Limericks
A Math Limerick is an expression which, when read aloud, matches the form of a limerick. The following is an example:
![\int_{1}^{\sqrt[3]{3}} z^2\, dz \,\times\, \cos \frac{3 \pi}{9} \,=\, ln \sqrt[3]{e}](../../../math/1/6/a/16a15175fc58dc6b8934ebdcbdc6f39c.png)
which reads as follows:
- The integral z-squared dz
- From one to the cube root of three
- Times the cosine
- Of three pi over nine
- Equals log of the cube root of e
[edit] Further reading
- Paul Renteln and Alan Dundes (2004-12-08). "Foolproof: A Sampling of Mathematical Folk Humor" (PDF). Notices of the AMS 52 (1).
