Mathematically Unconscious

Both of my sons sleepwalk. At least once a week, one of them will wake up an hour after bedtime, walk down the stairs, and start speaking gibberish. They have no idea what they’re saying, because they aren’t awake — even though their eyes are open. (Freaky!)

During a recent somnambulation, Alex stood at the top of the stairs. He appeared frustrated. Finally, he said:

I just need to find the numbers. It shouldn’t take long.

As you might well imagine, it’s a little scary to have your son walking and talking while asleep. The only solace is that his subconscious thoughts are about math.

I don’t sleepwalk. But I recently had a dream in which I attended a cocktail party and asked the other attendees a most unusual question:

I suspect that my 7 years as an editor and 4 years as a question writer for MathCounts are to blame, but that doesn’t make it any easier to accept.

I vividly remember a dream I had in college, on the night prior to my Linear Algebra midterm. Feeling unprepared for the exam, my nightmare consisted of two brackets pinching my head like a vice, while numbers floated past.

I awoke in a cold sweat at 5 a.m., and proceeded to a study carrel for more test prep.

I was happy to learn that other folks dream about math, too. While subscribed to a listserve for former instructors of the Center for Talented Youth, I received a message from Mark Jason Dominus that read, “I dreamt of the following problem while I was sleeping last night. When I woke up, I convinced myself that it was a good problem, so I’ve decided to share it.”

The volume of a 3 × 3 × 3 cube is 27 cubic units, and the volume of a 2 × 2 × 1 rectangular prism is 4 cubic units. Theoretically, six prisms should be able to fit inside the cube, with three cubic units empty. But can you arrange six 2 × 2 × 1 prisms so they fit inside a 3 × 3 × 3 cube?

Good luck, and sweet dreams!

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, surprised.

“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 — ?
Moo!

My 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.
Lemma who?
Lemma in, it’s raining!

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

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

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

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

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

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

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

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

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

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

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