Archive for June, 2013

Math from Car Talk

After stating this week’s Car Talk Puzzler, Tom and Ray said that the answer could be submitted via mail, email, or phone, and they gave the address, email address, and phone number. But their statement of the phone number was ambiguous. They said,

If you’d like to call us, the number is 1-888-CAR-TALK; that’s one-eight-eight-eight, two-two-seven, eight-five-squared-eight.

Near the end of the number, you’ll see that they included a “five-squared” to liven things up. No doubt, they did this to follow the lead of Ed Drewitz, a listener who suggested three alternative mnemonics for remembering the Car Talk phone number:

  • log-1 (10.27605439324)
  • 2662.8791941723
  • cos 79.11590889189° × 10,000,000,000

As part of a phone number, I was unsure how to interpret “five-squared.” Did it mean two 5’s? Or was it to be translated as 25, meaning a 2 and a 5? Converting TALK to the phone digits 8255, I was happy to see that 52 was meant to represent 25, which is what I had hoped but dubious that that’s what it was.

Later in the show, Ray and Tom discussed an interesting piece of research, which concluded that genius is passed from mothers to offspring, and that fathers have very little influence. This bummed me out. Three days ago, Alex told me, “A tablespoon is equal to 3 teaspoons, and that’s 12 quarter-teaspoons. We need 2 1/4 teaspoons, which is 9 quarters. So, we need to fill the tablespoon 9/12 full, which is 3/4.” That struck me as pretty good for a six-year-old — and I beamed with pride until I learned today that all of his mathematical acumen is likely derived from his mother. Ha-rumph.

There is, however, empirical evidence to the contrary. I recently read an article about wunderkind Jacob Barrett who has a 170 IQ and, at just 12 years old, was primed to become a paid research assistant in astrophysics. In an article in the Daily Mail, his mother Kristine Barnett admitted, “I flunked math. I know [Jacob’s ability] did not come from me.”

I don’t claim to have an IQ of 170, nor do I have a firm understanding of astrophysics. But my mother and Jacob’s mother seem to have a lot in common. My mother used to exclaim, “How the hell can x = 6, when x is a letter, and 6 is a number?”

God rest her soul. I hope she’s found peace in an algebra-free eternity.

June 30, 2013 at 4:28 pm Leave a comment

Best Math Joke Ever?

If you do a search for “best math joke ever,” you’ll see that there is widespread disagreement. The following are some of what you’ll find.

The folks at Physics Forums like this one:

How does a mathematician deal with constipation?
He works it out with a pencil.

Sadly, the site failed to include this follow-up joke.

What kind of pencil?
A #2 pencil, of course.

Some folks at Yahoo Answers like this one:

An infinite number of mathematicians walk into a bar. The first one orders a drink. The second one  orders half a drink. The third orders 1/4 drink. The fourth orders 1/8 drink, and so on. The bartender, a little overwhelmed, asks the mathematicians, “Hey, you guys sure you want to do this? Isn’t that a bit much?” The mathematicians reply, “Oh, don’t worry… we know our limits.”

From Mormon MD:

Pi Be Rational

And the good folks at Blue Donut have taken the list of 100 funniest jokes of all-time — as compiled by GQ — and allow visitors to vote on them. Sadly, most of them aren’t mathy, but this one from A. Whitney Brown is.

China has a population of a billion people. One billion! That means even if you’re a one in a million kind of guy, there are still a thousand others exactly like you.

June 25, 2013 at 2:43 pm 3 comments

How Much Does Your Name Cost?

Here’s a contrived yet fun math problem that I shared with my sons recently:

A local hardware store sells bronze letters. However, the letters vary in price; some are more expensive than others. When I was at the store the other day, four people purchased the letters in their names. Their names and the prices they paid were:

Aiden $491  •  Ned $225  •  Dane $399  •  Ed $135

The price of a name is equal to the sum of the prices of its letters. The price for uppercase and lowercase letters is the same, and there is no additional surcharge or tax. How much would the following people pay to buy the letters in their names?

Edna  •  Ian  •  Nadine

Those of you who know a little algebra will have no trouble with that problem. Those of you who don’t shouldn’t have too much trouble, either.

But then, I realized I could extend the problem for some added fun. And who am I to keep fun things to myself? So, here ya go.

I saw this sign in a window the other day:

Eli - $269

At first, I thought the store was engaging in human trafficking. But then I realized that $269 was the price for the bronze letters that had been used to spell the name Eli. Inside the store was a price list for other names:

AIDEN – 491 AL – 248 ART – 267 BEA – 290
EARL – 415 DANE – 399 ED – 135 ELI – 269
FAY – 220 GABI – 289 HAL – 284 IVY – 143
JACK – 234 JAY – 232 KO – 60 KAI – 283
LEXI – 272 MAVIS – 363 MAX – 215 NED – 225
PAT – 210 PERRI – 330 QI – 93 QUIN – 199
SAMMY – 338 WILL – 243 ZENO – 243

The store didn’t have a list of prices for the individual letters, but then I realized that I didn’t need one. From the table above, I could figure out how much my name  would cost.

Can you figure out how much your name would cost?

You can download both of these problems for use in a classroom (or at a mathy party) from the following link:

Name Letters (PDF)

And while I don’t believe in answer keys, you can check your work by using the form found on this page.

Name Letter Form

For what it’s worth, the longest name ever — according to Wolfe + 585, Senior, who has a pretty long name himself — is Rhoshandiatellyneshiaunneveshenk Koyaanisquatsiuth Williams. Her entire name name would have cost $4,073 at this store — an astounding $2,359 for her first name, $1,119 for her middle name, and a veritable bargain at $595 for her tame-by-comparison last name. (Incidentally, this is the name that appeared on her birth certificate. As the story goes, her father later increased her first name to 1,019 letters and added an additional 36 letters to her middle name. You know… just in case the name wasn’t long or unique enough already.)

June 21, 2013 at 9:52 pm 2 comments

Can You Find the Error?

I used to be the editor of the “Media Clips” column in the Mathematics Teacher journal. One objective of the column was to identify the use of incorrect mathematics in print. The following flyer from H. H. Gregg would have been a great example.

H H Gregg Flyer

My favorite entry in the “Media Clips” column was a clip from the Salt Lake Tribune on October 11, 2002, which read:

A Salt Lake County Health Department inspector paid a visit recently [to the Coffee Garden restaurant] and pointed out that research by the Food and Drug Administration indicates that one in four eggs carries salmonella bacterium, so restaurants should never use more than three eggs when preparing quiche. [The Coffee Garden’s quiche recipe calls for four fresh eggs.]


Anyway, back to H. H. Gregg. The image above may be too small or blurry to identify the error, so here’s an enlargement.

Flyer Bigger

I gave the flyer to my sons and told them that they could have ice cream for dessert if they were able to identify the math error. I’ll make the same offer to you — first person to post the error to the comments gets an ice cream cone from me.

June 17, 2013 at 1:49 am 16 comments

Math Teachers at Play 63

Hmm… let’s see… now where did I put my notes? I know that this is supposed to be the Math Teachers at Play blog carnival… but which one?

Maybe the following puzzle will help. In the grid below, do the following:

  • Circle any number, then cross out the other numbers in the same row and column.
  • Of the remaining nine numbers, circle one, then cross out the other numbers in the same row and column.
  • There should now be four numbers remaining; circle one. Then cross out the other numbers in the same row and column.
  • There should now be one number remaining. Circle it.
  • Calculate the sum of the four circled numbers.

PuzzlePretty cool, huh? Try it again, and you’ll find that the sum of the four circled numbers will always be 63. Can you figure out why it works?

Ah, yes! That’s it! This is Math Teachers at Play 63! Good day! Welcome one and all!

63 Road Sign

You might wonder why I’d start this carnival with so many questions. Maybe it’s because 63 is the ASCII code for a question mark.

Other interesting facts about 63:

  • 63 = 7 × 9.
  • 63 = 26 – 1 = 1 + 2 + 4 + 8 + 16 + 32.
  • The record for the longest field goal in NFL history is 63 yards–kicked by Tom Dempsey, Jason Elam, and Sebastian Janikowski.
  • 63 = 62 + 33.
  • ‘Rule 63’ is an online adage, which states that every fictional character has a counterpart of the opposite gender.
  • In Roman numerals, 63 is written as LXIII; and if you add the position of those letters in the alphabet, you get 12 + 24 + 9 + 9 + 9 = 63. It is the smallest number with this property. (Can you find the only other number with this property?)


Trying to help little kids see the fun and usefulness of math, Beanie N Us shows her daughter Learning about Numbers at the Car Park and having Fun with Math.

Elementary School

At the New Hope Elementary School, kids of all ages do M&M Math to learn about graphs, measurement, and area. Yum!

Fraction Folding, Discovery Learning is the first in a series of 16 blog posts that documents what a fourth-grade teacher at the Fourth Grade Studio did to help students develop conceptual understanding of fractions.

Navigating by Joy shares A Living Maths Approach to Angles using the book Sir Cumference and the Great Knight of Angleland and also shows how to have Fun With Tessellations.

When the Math Mama Writes, you better listen, especially when she’s questioning how and why we teach vocabulary in Writing, Vocabulary, and Teacher Inquiry.

Middle School

Offering straightforward and practical advice, The Numerist explains How to Write an Equation of the Line.

Who doesn’t love a story about student success? 4mulaFun shares such a story from a lesson that has students Reviewing Proportions with WKU. (Don’t know WKU? Neither did I! Read on.)

Miss Math Dork shares One of Her Favorite Activities for teaching measurement to middle schoolers, which is sure to become one of your favorites, too!

High School

Watch what happens when Mr. Chase alternately adds and multiplies in Arithmetic-Geometric Hybrid Sequences.

In Probabilities in a Painted Cube, Cut the Knot examines solutions to a problem about painting and cutting a larger cube into unit cubes and then  considers the historical problem of constructing a line that halves the area and the perimeter of a triangle in Area and Perimeter Splitters in a Triangle.

Math and Multimedia share 5 Fascinating Facts About Triangles That Will Surprise You.

Did you know that a Quadrilateral with Congruent Opposite Sides is a Parallelogram? Proofs from the Book will show you why.

Let’s Play Math tells us How To Master Quadratic Equations, with some assistance from James Tanton’s G’day Math Courses.


Are vectors too tough for mental math? Not according to White Group Maths, whose Vectors Mental Quiz demonstrates all the stuff you can calculate in your head without reaching for a computing device.

A mom and her kid at Moebius Noodles used concept maps to create Free To Learn by Peter Gray: Review and Infographics.

Charlotte Mason and Louis Benezet’s Thoughts on Math are documented by Triumphant Learning.

June 14, 2013 at 10:26 am 15 comments

Best Use of Math Textbooks

I had an ergonomics consultation last week, in which the specialist suggested that my monitor was too low. She said that I needed to raise it 6-8″ to be at an appropriate height, and since it will take more than a week to get the monitor stand, she had an alternate solution:

Monitor With Textbooks

I have over 50 textbooks on my bookshelf. I chose five that seem to be more effective at supporting my monitor than math education.

My colleagues are getting a good chuckle out of this.

June 12, 2013 at 9:48 am 2 comments

Math Jokes for National Doughnut Day

Today is National Doughnut Day, and if you need your fix, Time reports that free doughnuts are available from Dunkin’ Donuts, Krispy Kreme, Tastykake or Winn Dixie.

TorusAt MJ4MF, we can’t let this day pass without telling the obvious joke…

A topologist is a mathematician who can’t tell a coffee cup from a doughnut.

And the modification…

How many topologists does it take to change a light bulb?
Just one. But what’ll you do with the doughnut?

To help you celebrate, here’s a doughnut-related math problem.

Several years ago, Dunkin’ Donuts ran a commercial bragging about how picky they were. The commercial stated:

We reject more than one million pounds of coffee beans a year.

Sure sounds impressive, doesn’t it? But how picky are they, really? Do a back-of-the-envelope estimate, and I think you’ll realize that they’re not all that picky after all.

June 7, 2013 at 12:46 pm 3 comments

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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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