Posts tagged ‘joke’

12 Math Knock-Knock Jokes

In a very old Second City skit, a man on hold complained (to no one in particular) about the hold music. After his complaint, a voice on the other end of the line said, “I’m sorry. Don’t you like my singing?”

“Who are you?” he asked.

“I’m your hold operator. If you don’t like music, I’d be happy to entertain you in some other way. Would you like to hear a joke?” she asked.

“Um… sure, why not?”

“It’s a knock-knock joke,” she said. “Are you familiar with the format?”

Now, that’s just funny!

My favorite joke to tell in the classroom is a knock‑knock joke, so I hope that you are familiar with the format.

Knock, knock.
Who’s there?
Interrupting cow.
Interrup — ?

GRiNMy sons are now of an age where they can understand jokes, and those of the knock‑knock variety are told daily in our house. (The knock-knock jokes at GRiN are a source of endless amusement.) Sadly, I didn’t know any knock‑knock jokes that are mathy… so I made some up. Here they are, 12 totally original (sort of) but not terribly funny math knock-knock jokes. Aren’t you glad you stopped by today?

Knock, knock.
Who’s there?
Lemma who?
Lemma in, it’s raining!

Knock, knock.
Who’s there?
Mode who?
Mode the lawn. What should I do next?

Knock, knock.
Who’s there?
Slope who?
Slope ups should stay on the porch.

Big Dogs

Knock, knock.
Who’s there?
Convex who?
Convex go to prison!

Knock, knock.
Who’s there?
Prism who?
Prism is where convex go!
(Weren’t you paying attention to the previous joke?)

Knock, knock.
Who’s there?
Origin who?
Vodka martini origin fizz?

Knock, knock.
Who’s there?
Zeroes who?
Zeroes as fast as she can, but the boat doesn’t move.

Knock, knock.
Who’s there?
Unit who?
Unit socks; I knit sweaters.

Knock, knock.
Who’s there?
Outlier who?
Outlier! We only let honest people in this house!

Knock, knock.
Who’s there?
Möbius who?
Möbius a big whale!

Knock, knock.
Who’s there?
Tangents who?
Tangents spend a lot of time at the beach.

Knock, knock.
Who’s there?
Axis who?
Axis for chopping, saw is for cutting.

September 22, 2012 at 12:38 pm 1 comment

Ordered Pairs, Gumby, and Palindromes

My sons recently received green, flexible toys from their aunt. When I turned on my calculator today, it read:


I’m not sure why it’s an ordered pair, but seeing that on my calculator screen cracked me up.

Gumby Graph

Then tonight at dinner, they made up their own knock-knock joke:

Knock, knock.
Who’s there?
Gumby who?
Gumby more fun to chew than anything else!

While I’m happy that my four-year-old sons have a sense of humor, it’s their love of math that I most appreciate. Yesterday in the car, Eli noted that the time was 6:16 p.m. “Palindrome!” he shouted.

“Actually,” Alex said, “any time that it’s six, colon, number, six, it’s a palindrome.”

“That’s right,” I said. “How many times a day do you think the time is a palindrome?”

Eli guessed 50. Alex guessed 70. But those were clearly random guesses. I asked if they could figure it out.

“We could count them,” Eli suggested.

“No,” Alex said. “An easier way is, ‘What is 24 × 6?’”

“Why would 24 × 6 give you the answer?” I asked, mainly because I was sure he didn’t know.

“Because there are 24 hours in a day,” he said, “and there are 6 times each hour — when the middle number is 0, 1, 2, 3, 4, or 5.” He then used the distributive property to calculate 24 × 6 = (20 + 4) × 6 = 120 + 24 = 144.

“No,” Eli said. “There aren’t 6 palindromes at 10 o’clock.”

They discussed it for a while, and they agreed that there was only one palindrome of the form 10:_1, 11:_1, and 12:_1. And using that piece of info, they jointly concluded that there are 18 hours in a day with 6 palindromes and 6 hours in a day with just 1 palindrome, giving a total of 114 palindromes per day.

Though none of them are as good as these:

One? No!
Six axis.
Seven eves.
Nine men in. (A palindrome about nine, with nine letters, and an allusion to baseball, which has nine players per team. Sweet!)

Some people love the smell of napalm in the morning, but I love listening to two kids solve a math problem. I may even love it more than I love a good Gumby joke!

March 2, 2012 at 10:44 pm Leave a comment

Jokes for Another Day

A warm-up question to prepare you for the jokes that follow:

Name four days that start with the letter T.

A joke for the Celsius crowd…

“It’s freezing outside!” she said.

“I know,” he replied, “and it’s supposed to be twice as cold tomorrow!”

A sentiment shared by too many students…

Mother: Did you learn a lot in school today?

Son: Apparently not! I have to go back tomorrow!

If only this didn’t seem so believable…

Teacher: Tomorrow, Dr. Feynman is giving a lecture on Saturn, and everyone must attend.

Student: Wow, can you get there in just one day?

Ever have a professor like this?

When the student went to his logic professor for help, she replied, “Come back tomorrow.” The student returned the next day and was given the same instructions. The student returned every day, and every day he was told, “Come back tomorrow.”

Finally, the professor lost her patience. “This  is outrageous!” she said to the student. “Don’t you understand simple language? I keep telling you to come tomorrow, yet you insist on coming today!”

And finally, a joke about yesterday…

“My math teacher is crazy,” Johnny told his mom. “Yesterday, she told us that 5 = 4 + 1. Today, she said that 5 = 3 + 2!”

November 15, 2011 at 5:14 pm Leave a comment

5 (or Maybe 6) More Math Jokes

Five FingersI asked an actuary to calculate the number of jokes that have been posted on the MJ4MF blog.

He replied immediately and definitively, “1005.”

“Wow, how did you count them so fast?” I asked.

“Well, there are 5 jokes below,” he said, “and about a thousand in the archives.”

The young math professor had not had a paper accepted for publication in almost four years. Feeling a little discouraged, he considered quitting and becoming a fisherman. But he quickly realized that he wouldn’t be able to survive on his net income.

The surgeon asked a heart transplant patient, “What kind of heart would you like to receive?”

“How about one from a statistician,” the patient says. “That way, I’ll know it’s never been used.”

What’s the difference between an actuary and an accountant?
About $50,000.

If you took all of the actuaries in New Jersey and laid them end-to-end on the NJ Turnpike… would anyone care?

Feeling a little hungry, f(x) = x2 + 3 walks into a restaurant. “Got any sandwiches?” he asks.

“Sorry,” says the waiter, “we don’t do catering for functions.”

September 30, 2011 at 11:00 am Leave a comment

Jokes In Order

“Daddy,” said Eli, “there’s a new math joke we need to tell you.”

“Really?” I said. “Where did you hear this joke?”

“I made it up,” Eli said.

“Well, then, let’s hear it!”

What did 0 say to 10?
Nice one!

Okay, so maybe it’s not a knee-slapper… but I still think it’s pretty cool that my 4-year-old son created a math joke.

I especially liked that he made up his joke about 10 on the 10th of September; more specifically, on the sequential date 9/10/11. Here’s a joke about sequences:

Being without you is like being a metric space in which a Cauchy sequence exists but does not converge.

The date 9/10/11 is also interesting in Roman numerals — it is IX/X/XI, which is a palindrome. How many other sets of three consecutive Roman numerals, when taken in order, form a palindrome?

September 10, 2011 at 11:21 pm 4 comments

Why Are Math Jokes Funny?

There’s a demotivational poster that reads:

If you get them, you probably don’t have friends.


You may not have friends, but if you laugh at a math joke, then you have something in common with the person who wrote, forwarded, or posted the joke. Is that person a friend? Maybe not, but she is at least a kindred spirit.

Harvey Penick wrote the book And If You Play Golf, You’re My Friend. For our crowd, if you laugh at math jokes, then you’re my friend.

This got me to thinking about what makes a math joke funny and why we enjoy them. I found my favorite answer to this question in the comments section of a webcomic. One comment suggested that part of the reason we find math jokes funny is that we “like inside jokes, probably because they exclude other people.” But a response to that comment suggested that shared dorkiness may be the reason:

It’s not that you laugh and think, “Neener, neener — I get it, and you don’t.” It’s that you realize you are not alone, and that sensation is bliss.

The mention of bliss reminded me of a joke…

Would you rather have eternal bliss or a ham sandwich?
A ham sandwich, because nothing is better than eternal bliss, and a ham sandwich is better than nothing.

If you laughed at that joke, take comfort in knowing that you’re not alone and that you’re my friend.

August 20, 2011 at 5:42 am Leave a comment

Good Jokes and Great Problems

You may or may not agree with the following contention. (Typing that sentence made me think, “The law of the excluded middle either rules or does not rule.”)

A good joke is like a good math problem…
You don’t expect the punch line,
And you have to think to figure it out.

One problem for which this maxim holds is Paper Pool. The problem can be found in the unit Comparing and Scaling: Ratio, Proportion, and Percent, which appears in the middle-grades Connected Math Project curriculum. It also appears in 1000 Play Thinks by Ivan Moscovich as Playthink 833: Reflected Balls.

The rules for Paper Pool are rather straightforward. Create a rectangular pool table with integer dimensions that has a pocket at each of the four corners. Then following the rules below, in which pocket will the ball land, and how many hits will occur?

  • The lower-left corner is always corner A, and the labeling continues counterclockwise with B, C, and D.
  • The ball always starts in corner A.
  • The ball is hit with an imaginary cue (a stick for hitting a pool ball) so that it travels at a 45° diagonal across the grid.
  • If the ball hits a side of the table, it bounces off at a 45° angle and continues its travel.
  • The ball continues to travel until it hits a pocket.

For example, a 5 × 3 table is shown below. Following the rules above, the ball will land in Pocket C after 8 hits. (Note that the initial strike by the cue stick at A and reaching the pocket at C are both counted as hits. You can disagree if you like, but using these conventions will make it easier to see some patterns.)

PaperPool - 5 x 3 Table

How many hits do you think will occur on a 5 × 4 table? Go ahead, take a second to think about it…

If you predicted that 9 hits would occur, you’re right:

Paper Pool - 5 x 4 Table

You can now see a pattern begin to emerge:

5 × 3 → 8 hits
5 × 4 → 9 hits

So, then, how many hits will occur on a 5 × 5 table? Given the pattern above, it would be reasonable to think that 10 hits would occur. But that would be wrong…

Paper Pool - 5 x 5 Table

Like the punch line to a good joke, this result was unexpected. At this point, most people want to figure out what’s going on.

If you’re like most people, then you can explore Paper Pool using the Online Paper Pool Tool at Illuminations.

Finally, here’s a joke that really does have an unexpected punch line.

Will you be able to attend the 2012 International Convention of the Barbershop Harmony Society in Portland?  You really should try to make it — it’s bound to be a harmonic function


August 15, 2011 at 9:46 am Leave a comment

Real-Life Double Negatives

“Can a Jewish person eat a ham calzone?” I asked my Jewish friend.

She gave me a look that said, “Oh, goodness, I can’t wait to hear this one…”

I continued. “It seems to me that things cancel out. You’re not allowed to eat ham, but you also aren’t allowed to mix meat and cheese, so this is a double negative.”

“Nice try,” she replied. “Just means you get to ride the express elevator to hell.”

The error with my logic, of course, is that sins are additive, not multiplicative. This is actually quite lucky, if you think about it. Otherwise, you’d have to spend your entire life being remarkably fastidious in keeping track of your sins: an even number of sins, you go to heaven; an odd number of sins, you end up a little lower. The graph looks something like this:


I’m not the first to tell a joke involving Jews and double negatives. Stanislaw Ulam did it with this joke from his autobiography:

Two Jews are riding on a train through Russia. One asks the other, “Where are you going?” The second replies, “To Kiev.” Whereupon the first says, “You liar, you tell me you are going to Kiev so I would think you are going to Odessa. But I know you are going to Kiev, so why do you lie?”

July 7, 2011 at 6:24 am 3 comments

The Humor and Poetry of Jims Maher

Yesterday, I received an email from Jims Maher containing the following joke, which he said he thought up yesterday in a real “facepalm” moment:

There used to be seven bridges in Königsberg.
Two were lost to war. Another two were demolished in peace.
So what does that leave us with? 

A slippery slope.

Coincidentally, Jims was also the only entrant in the MJ4MF Humorous Math Poem Contest. (I will assume that everyone chose not to submit an entry because I announced the contest on April 1, so all of you thought the contest was a joke. Please allow me to harbor this delusion — it’s easier on my ego that way.) Consequently, a signed copy of MJ4MF is on its way to Jims. He said that he plans to “put it to good use as a prize in some fundraiser.” I like your style, Jims!

Because enquiring minds want to know, here is Jims’ award-winning poem…

Start at One

Numbers are counted.
One, two, three…
But some numbers are skipped,
It’s plain to see.

We never count zero
Because it’s not there.
And the imaginary numbers
Are as visible as air.

It is only the natural numbers
That we will count,
From one on up
To any amount.

However, the last number
Can never be known,
Because you can always add one,
However high that you go.

And so we keep counting,
From one, to two, to three…
With the natural numbers we keep counting,
From one to infinity.

Forgive the commentary, but I could not help thinking about mathematical definitions when reading Jims’ poem. According to Wolfram MathWorld,

The term “natural number” refers either to a member of the set of positive integers 1, 2, 3, …, or to the set of nonnegative integers 0, 1, 2, 3, …. Regrettably, there seems to be no general agreement about whether to include 0 in the set of natural numbers.

Similarly, the James and James Mathematical Dictionary gives three different definitions for whole numbers: The set of positive integers 1, 2, 3, …; the set of nonnegative integers 0, 1, 2, 3, …; and the set of all positive and negative integers …, -2, -1, 0, 1, 2, ….

May 5, 2011 at 11:08 pm 3 comments

I Like My Women Like I Like My Math

My father had a predilection for embarassing my mother. For instance, when a waitress would ask how he’d like his coffee, he’d say:

I like my coffee like I like my women — hot, sweet, and light.

My father was the original bigot chauvinist. Had I been taking notes, I could have written Sh*t My Dad Says twenty years ago.  Here are a few other similes that I think my father would have appreciated:

I like my women like I like my mathematics — pure and beautiful, not complex and irrational.

I like my women like I like my math tests — full of problems, and easy to cheat on.

I like my women like I like my math problems — simple and easy.

I like my women like I like my calculus textbooks — full of curves.

I like my women like I like my research papers — interesting, intelligent, and covered in ink.

I like my women like I like my data — average, and within my range. 

I like my women like I like my equations — well-balanced.

I like my women like I like the tenth positive odd number — prime, and over 18.

I like my women like I like my ellipses whose major and minor axes are almost equal — just a little eccentric.

I like my women like I like the roots of x2 + 2x + 1 = 0 — degenerate, and easy to find.

I like my women like I like my calculator-dependent students — with no interest in multiplying.

February 18, 2011 at 9:49 am Leave a comment

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About MJ4MF

The Math Jokes 4 Mathy Folks blog is an online extension to the book Math Jokes 4 Mathy Folks. The blog contains jokes submitted by readers, new jokes discovered by the author, details about speaking appearances and workshops, and other random bits of information that might be interesting to the strange folks who like math jokes.

MJ4MF (offline version)

Math Jokes 4 Mathy Folks is available from Amazon, Borders, Barnes & Noble, NCTM, Robert D. Reed Publishers, and other purveyors of exceptional literature.


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