## Fortune Bank Teller

One of the radio commercials in the GEICO “Surprising” campaign features a fortune bank teller who dispenses both greenbacks and prognostications. The commercial ends with the teller saying,

I see a yellow light serpent… and a low APR.

What you may also find surprising is that this commercial reminds me of my father-in-law, Julian Block, a nationally known tax expert. Julian used to work for a company that connected advisors to people seeking help. An operator would ask a few questions of each caller and then connect the advisee with an appropriate consultant. Sometimes, however, the advisee would be connected to the wrong expert. And the problem? The company specialized in dispensing two types of advice: tax and psychic.

You may now see why the GEICO commercial reminds me of my father-in-law. When calls were incorrectly routed to him, he would become a de facto psychic tax advisor. I imagine conversations like the following:

Young Woman: My boyfriend just proposed. Should I marry him?

Julian: That depends. What’s his tax bracket?

These combinations — fortune teller and bank teller; psychic advisor and tax advisor — yield rather whimsical new professions. It made me wonder if there were others. Sadly, an hour of brainstorming yielded only a handful of satisfactory results:

Super Hero Intendent, who still has time to fight crime after 8 hours of dealing with stopped-up toilets

Dog Street Walker, who thinks the oldest profession is picking up Spot’s poo

Antique Debt Collector, who will accept payment in Ming vases and pocket watches

Switchboard Lottery Operator, who has a 1-in-500 chance of connecting you to the right person

Social Construction Worker, who can strike up a conversation with anyone while shingling a roof

Foreign Language Flight Instructor, who will teach you how to land safely after you give her the declension for agricola

Got any others you’d add to the list? Post them in the comments.

## Stick Figure Math

I’ll never forget the first time I saw the pattern

1, 2, 4, 8, 16, __

and was dumbfounded to learn that the missing value was 31, not 32, because the pattern was not meant to represent the powers of 2, but rather, the number of pieces into which a circle is divided if n points on its circumference are joined by chords. Known as Moser’s circle problem, it represents the inherent danger in making assumptions from a limited set of data.

Last night, my sons told me about the following problem, which they encountered on a recent math competition:

What number should replace the question mark?

Well, what say you? What number do you think should appear in the middle stick figure’s head?

Hold on, let me give you a hint. This problem appeared on a multiple-choice test, and these were the answer choices:

1. 3
2. 6
3. 9
4. 12

Now that you know one of those four numbers is supposed to be correct, does that change your answer? If you thought about it in the same way that the test designers intended it, then seeing the choices probably didn’t change your answer. But if you didn’t think about it that way and you put a little more effort into it, and you came up with something a bit more complicated — like I did — well, then, the answer choices may have thrown you for a loop, too, and made you slap your head and say, “WTF?”

For me, it was Moser’s circle problem all over again.

So, here’s where I need your help: I’d like to identify various patterns that could make any of those answers seem reasonable.

In addition, I’d also love to find a few other patterns that could make some answers other than the four given choices seem reasonable.

For instance, if the numbers in the limbs are a, b, c, and d, like this…

then the formula 8a – 4d gives 8 for the first and third figures’ heads and yields 8 × 6 – 4 × 9 = 12 as the answer, which happens to be one of the four answer choices.

Oh, wait… you’d don’t like that I didn’t use all four variables? Okay, that’s fair. So how about this instead: ‑3a + b + c – 2d, which also gives ‑3 × 6 + 7 + 5 + 2 × 9 = 12.

[UPDATE (3/9/18): I sent a note to the contest organizers about this problem, and I got the following response this afternoon: “Thanks for your overall evaluation comments on [our] problems, and specifically for your input on the Stick Figure Problem. After careful consideration, we decided to give credit to every student for this question. Therefore, scores will be adjusted automatically.”]

## Six Degrees of Titillation

It was 75° today. If you live in Honolulu, Karachi, Gaberone, or Rio de Janeiro, that might not strike you as unusual. But let me assure you that during late February in Crofton, MD, a temperature that high is rather unexpected.

But no complaints. It was nice to wear only a t-shirt and no jacket, and it allowed me to use this joke at the start of my presentation:

What a beautiful day! When I was invited to this event, I suspected it’d be close to 20° outside. I just didn’t realize it’d be Celsius.

Horrible, ain’t it? But don’t worry… I’ve got more:

• If it’s 0° today, and it’s supposed to be twice as cold tomorrow, how cold is it going to be? (Stephen Wright)
• Are you a 45° angle? Because you’re acute-y.
• Why did the obtuse angle go to the beach? Because it was more than 90°.
• Are you cold? Go sit in a corner. It’s 90° over there.
• Why didn’t the circle go to college? It already had 360 degrees.
• I asked the trigonometer what the weather was like, and he said it was 15π/16 outside.
• The number you dialed is imaginary. Please rotate your phone 90° and try again.
• What brand of deodorant did the angle use? Degree.

## A Mathematical Thank-You Note

I recently sent a copy of More Jokes 4 Mathy Folks to a friend of an acquaintance, and today I received a thank-you letter from the recipient. I think the letter is worth sharing, so here you go:

Patrick —

Thanks so much for sending me More Jokes… I’ve already annoyed my entire family, and I’m only 46/111 through the book. (I think your work here is done.)

I can’t provide a formal proof, but empirically speaking, this is the best collection of math jokes known to exist. Honestly, I enjoy the blend of quips and jokes; almost everything I read translates well into a groaner I can splice into my physics classroom repertoire!

Hoping you don’t object to the informality of my “stationery” — thought you’d appreciate the utility of engineering paper.1

Thanks again! Best,
Rob

P.S. I noticed — when I looked up your address (ed. note: STALKER!) — that we only live about seven root two2 minutes apart. How would you feel about raising a pint some evening? I’d love to hear about your work and exchange a few quips!

This is one of the nicer letters I’ve received, and it was fun to be reminded that not all mail needs to be electronic. And you can bet that some of those compliments will be used on a promotional flyer soon!

1 Quarter-inch quadrille paper, if you must know.

2 He had correctly written the irrational number as

$7\sqrt{2}$

but since LaTeX looks like shit as inline text, I converted it to straight English.

From Gene Weingarten’s recent column, “Rhymes Against Humanity,” in the January 28 edition of the Washington Post Magazine:

An infinite number of mathematicians
Walked into a bar on one recent night,
And, under the strangest of barroom conditions,
What followed quite nearly became a big fight.

“I’ll have a pint,” said the first to the ’tender.
“I’ll have a half,” said the next fellow down.
“I’ll have a quarter,” said the third (no big spender).
“Give me an eighth,” said the next, like a clown.

The bartender fumed and grew suddenly pale
Then, calmly, he turned and he went to the spout
Drew up two pints, set them down at the rail.
Said, “Enough of this nonsense — you all work it out.”

This is an MJ4MF original, though like Gene’s, it’s based on a stale, old joke:

With my head in an oven
And my feet on some ice,
I’d say that, on average,
I feel rather nice!

What other classic math jokes can be easily converted to poems? Or have already been?

## Stupid Stats

C’mon, now… really?

Uterine size in non-pregnant women varies in relation to age and gravidity [number of pregnancies]. The mean length-to-width ratio conformed to the golden ratio at the age of 21, coinciding with peak fertility.

Claiming that a uterine golden ratio coincides with peak fertility is highly suspect. The good folks at Ava Women claim that, “Most women reach their peak fertility rates between the ages of 23 and 31.” Information at Later Baby states, “Female fertility and egg quality peak around the age of 27.” And WebMD says, “A woman’s peak fertility is in her early 20s.” So, there seems to be some debate about when peak fertility actually occurs. Consequently, this strikes me as retro-fitting, and it seems that Dr. Verguts and his colleagues may have played loose with the age of peak fertility in order to make a connection to the golden ratio.

In their defense, though, it’s not the first time that folks have gone uptown trying to find a connection to the golden ratio. A claim by The Golden Number states, “[The DNA molecule] measures 34 angstroms long by 21 angstroms wide for each full cycle of its double helix spiral,” and 34/21 ≈ 1.6190476, which is approximately equal to φ, 1.6180339.

Though this guy — an honest-to-goodness biologist — seems to disagree:

I’ve also heard folks say that people are perceived as more beautiful if certain bodily proportions are in the golden ratio. The most extreme example of this that I’ve found involves the teeth:

…the most “beautiful” smiles are those in which central incisors are 1.618 wider than the lateral incisors, which are 1.618 wider than canines, and so on.

In a study of 4,572 extracted adult teeth, Dr. Julian Woelfel found the average width of the central incisor to be 8.6 mm. If the teeth in a beautiful smile follow the geometric progression described above, well, that would imply that the first molar would be just 8.6 × 0.6185 ≈ 0.8 mm wide, which isn’t reasonable and, moreover, is not even remotely close to the average width that Dr. Woelfel found for the first molar: approximately 10.4 mm.

But all of these claims involving the golden ratio are not even close to being the stupidest statistics I’ve heard in my life. Mary Anne Tebedo made a remark on the floor of the Colorado State Senate in 1995 that may hold that distinction:

Statistics show that teen pregnancy drops off significantly after age 25.

Of course, it’s hard to call that a statistic, since it’s completely nonsensical. Maybe it’s only the stupidest statement I’ve ever heard.

Then there’s this one, from the New York Times on August 8, 2016, which couldn’t be more useless:

No presidential candidate has secured a major party nomination after an FBI investigation into her use of a private email server.

Well, duh. Email didn’t even exist before the 1970’s. Moreover, besides Hillary Clinton, has any presidential candidate ever had their use of a private server investigated by the FBI? This is like saying, “No one has ever been named People‘s Sexiest Man Alive after writing a math joke book.” (Not yet, anyway.)

Randall Munroe made fun of these types of “no politician has ever…” claims in 2012 with his cartoon Election Precedents:

And it’s true:

But perhaps my all-time favorite is one that Frank Deford — may he rest in peace — included in his piece “The Stupidest Statistics in the Modern Era” on NPR’s Morning Edition:

He’s [Brandon Phillips] the first National League player to account for as many as 30 steals and 25 double plays in one season.

About this stat, Deford commented, “Steals and double plays together? This is like saying, ‘He’s the first archaeologist to find 23 dinosaur bones and 12 Spanish doubloons on the same hunt.'” (I sure am going to miss him.)

The preponderance of dumb stats shouldn’t come as a surprise, though. A recent study found that people deemed real news headlines to be accurate 83% of the time and fake news headlines to be accurate 75% of the time. So, if we can’t tell truth from fiction, how can we possibly distinguish useful statistics from inane?

If you’d like to test your ability to detect fake news, check out Factitious from American University.

## WODB, Quora Style

The following puzzle was recently posted on Quora:

Which of the following numbers don’t belong: 64, 16, 36, 32, 8, 4?

What I liked about this puzzle was the answer posted by Danny Mittal, a sophomore at the Thomas Jefferson High School for Science and Technology. Danny wrote:

64 doesn’t belong, as it’s the only one that can’t be represented by fewer than 7 binary bits.

36 doesn’t belong, as it’s the only one that isn’t a power of 2.

32 doesn’t belong, as it’s the only one whose number of factors has more than one prime factor.

16 doesn’t belong, as it’s the only one that can be written in the form xy, where x is an integer and y is a number in the list.

8 doesn’t belong, as it’s the only one that doesn’t share a digit with any other number in the list.

4 doesn’t belong, as it’s the only one that’s a factor of all other numbers in the list.

I suspect that Danny has visited Which One Doesn’t Belong or has read Christopher Danielson’s Which One Doesn’t Belong. Or maybe he’s just a math teacher groupie and trolls MTBoS.

But then Jim Simpson pointed out the use of “don’t” in the problem statement, which I had assumed was a grammatical error. Jim interpreted this to mean that there must be two or more numbers that don’t belong for the same reason, and with that interpretation, Jim suggested the answer was 32 and 8, since all of the others are square numbers.

Don’t get me wrong — I don’t think this is a great question. But I love that it was interpreted in many different ways. It could lead to a good classroom conversation, and it makes me consider all sorts of things, not the least of which is standardized assessments. How many times have students gotten the wrong answer for the right reason, because they interpreted an item on a state exam or the SAT differently than the author intended? And how many times have we bored students with antiseptic questions, only because we knew they’d be free from such alternate interpretations? Both scenarios make me sad.

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.