Archive for June, 2014

Math in France

Math in FranceDriving through the French countryside using smartphone GPS for navigation is a lot like driving through rural Pennsylvania with my redneck cousin riding shotgun — there is a significant lack of sophistication, an ample amount of mispronunciation, and myriad grammatical errors.

In Pennsylvania:

Take that there right onto See-Quo-Eye-Ay (Sequoia) Drive.

In France:

At the roundabout, take the second right toward Ow-Bag-Nee (Aubagne).

Take D51 to Mar-Sigh-Less (Marseilles).

And of course, the GPS pronounced the coastal town of Nice like the adjective you’d use to describe your grandmother’s sweater, though it should sound more like the term you’d use to describe your brother’s daughter.

I was half expecting the computer voice to exclaim,

Hey, cuz, watch this!

Otherwise, the rest of my recent week-long trip to the south of France was intellectually and often mathematically stimulating. The image below shows a -1 used to describe an underground floor (parking) in a hotel:

Elevator, -1

And though I didn’t get a picture, the retail floor of the parking garage at the Palais de Papes in Avignon was labeled 0, with the three floors below for parking labeled -1, -2, and -3.

This is a country that does not fear negative integers.

I also noticed that the nuts on fire hydrants in Aix-en-Provence were squares.

Fire Hydrant - Square

Hydrant with Square Nut

The nuts on American hydrants used to be squares, until hoodlums realized that two pieces of strong wood could be used to remove them, release water into the streets, and create an impromptu pool party for the neighborhood. As a result, pentagonal nuts are now used on most hydrants.

Alas, an adept hoodlum can even remove pentagonal nuts, so some localities have replaced them with Reuleaux triangle nuts, like the ones on hydrants outside the Philadelphia convention center, which can only be removed with a specially forged wrench.

Hydrant Reuleaux

Hydrant in Philadelphia
with Reuleaux Triangle Nut

But perhaps the most mathematical fun that France has to offer is the Celsius scale. While there, our cousins taught my sons a poem for intuitively understanding the Celsius scale:

30 is hot,
20 is nice,
10 is cold,
and 0 is ice.

And I was able to teach them a formula for estimating Fahrenheit temperatures, which is easy to calculate and provides a reasonable approximation:

Double the (Celsius) temperature, then add 30.

Or algebraically,

F = 2C + 30

The actual rule for converting from Fahrenheit to Celsius is more familiar to most students:

F = 1.8C + 32

This rule, however, sucks. It’s not easy to mentally multiply by 1.8.

My sons were not convinced that the rule for estimating would give a close enough approximation. I showed them a table of values from Excel:

Temp Conversion Actual vs Estimate

I also showed them a graph with the lines y = 1.8x + 32 and y = 2x + 30:

Celsius - Actual vs Estimate

With both representations, it’s fairly clear that the estimate is reasonably close to the actual. For the normal range of values that humans experience, the estimate is typically within 5°. Even for the most extreme conditions — the coldest recorded temperature on Earth was -89°C in Antartica, and the hottest recorded temperature was 54°C in Death Valley, CA — the Fahrenheit estimates are only off by 9° and 20°, respectively. That’s good enough for government work.

And here’s a puzzle problem for an Algebra classroom, using this information.

The Fahrenheit and Celsius scales are related by the formula F = 1.8C + 32. But a reasonable estimate of the Fahrenheit temperature can be found by doubling the Celsius temperature and adding 30. For what Celsius temperature in degrees will the actual Fahrenheit temperature equal the estimated Fahrenheit temperature?

It’s not a terribly hard problem… especially if you look at the table of values above.

June 25, 2014 at 9:39 am 2 comments

Pearls of Wisdom

Although most educators are unaware that the following quotation was coined by Anna Isabella Thackeray Ritchie, almost all of them have heard it before.

Give a man a fish, feed him for a day.
Teach a man to fish, feed him for a lifetime.

It originally appeared in Mrs. Dymond as, “If you give a man a fish, he is hungry again in an hour. If you teach him to catch a fish, you do him a good turn.”

A modification of this quotation is similarly poignant and more colorful.

Build a man a fire, warm him for a day.
Set a man on fire, warm him for the rest of his life.

There are more direct modifications of the phrase:

  • Teach a man to fish, and you can sell him a ton of accessories.
  • Give a man a fish, and you’ll feed him for a day.
    Teach a man to fish, and he’ll drink beer all day.
  • Give a man a fish, feed him for a day.
    Don’t teach a man to fish, feed yourself.
    He’s a grown man. Fishing’s not that hard, dude.

There are other motivational quotations that I’ve heard throughout my life. One inspired the following image:

Removed BonesA similar pontification has been making its way around the Internet recently, but it gives me pause.

Population Around the Equator

The math of this declaration is highly troubling. Assuming each of the 7 billion people on Earth stood side-by-side and held hands with two other humans, and each of them occupied approximately two feet of width, their entire length would be 2.7 million miles. That’s more than 100 times the distance around the Earth at the equator.

Using that same estimate — two feet of width per person — it would only take about 65 million people to circle the Earth at the equator. So a better version of this joke might be:

If everyone from California and Texas held hands around the equator, a significant portion of them would drown.

The problem with this modification is obvious. There are those who believe that sacrificing all Californians would be justified if it means being rid of all Texans; and there are those who believe that sacrificing all Texans would be justified if it means being rid of all Californians.

I’ll continue to work on a better modification, but I’d love to hear some suggestions from you.

June 15, 2014 at 11:11 am Leave a comment

13 Math Jokes that are PG-13 (or Worse)

Triskaidekaphobia is an abnormal fear of the number 13. If you suffer from this ailment, then you might want to stop reading now.

Today is the only Friday the 13th that will occur in 2014. Which makes it a good day for some trivia questions.

  • Is there at least one Friday the 13th every year? If so, prove it. If not, provide a counterexample.
  • What is the maximum number of times that Friday the 13th can occur in a (calendar) year?
  • What is the average number of times that Friday the 13th occurs in a year?

You can check out my previous post Good Luck on Friday the 13th to find the answers to those questions.

This is also a good day for some off-color math jokes. Then again, is there a bad day for off-color math jokes?

Why is 1 the biggest slut?
It goes into everything.

What has six balls and abuses the poor?
The lottery.

Math is a collection of cheap tricks and dirty jokes.

What do calculus and my penis have in common?
Both are hard for you.

Old statisticians never die.
They just get broken down by age and sex.

Algebraists do it in fields.
Or do they do it in groups?

What do you call an excited quadrilateral?
An erectangle.

What covers the genitalia of a hexahedron?
Cubic hair.

A knight with a 20-inch penis told a wizard that he wanted a smaller penis. The wizard told him to propose marriage to an enchanted princess. He did, and the princess said, “No.” His penis instantly shrunk to 16 inches. Happy with this result, he asked her again. Again she said, “No,” and his penis shrunk to 12 inches. He realized that each time she said, “No,” his penis shrunk by 4 inches. So he asked one last time. “How many times do I have to refuse you?” she asked. “No! No! No!”

How is math like sex?
I don’t get either one.

How is sex like fractions?
It’s improper for the larger one to be on top.

Why did you break up with that math student?
I caught her in bed, wrestling with three unknowns.

13 is the square root of 169. What is the square root of 69?
Ate something.

June 13, 2014 at 1:13 pm Leave a comment

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.

Past Posts

June 2014

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