Archive for November, 2010

Warning Labels

Don’t you wish there were more truth in advertising? I applaud the efforts of the surgeon general, the FDA, the EPA, and others in their recent attempts to make consumers aware of the potential dangers of products. But the current warnings merely scratch the surface of the imminent dangers posed.

It might also be wise to include mention of the following danger, in light of discoveries during the past century:

There is an extremely small but non-zero chance that, through a process known as “tunneling,” this product may spontaneously disappear from its present location and reappear at some random place in the Universe, including your neighbor’s medicine chest. The manufacturer is not reponsible for any damage or inconvenience that this may cause.

In fact, there are inherent dangers in the labels that currently appear on products…

How do you keep a programmer in the shower for hours?
Give him a bottle of shampoo that says, “Lather, Rinse, Repeat.”

November 29, 2010 at 9:32 am Leave a comment

Thanksgiving Jokes

So, maybe they’re not mathy… but the following jokes are appropriate for today…

The young turkey graduated high honors with a math degree, but he returned home and seemed reluctant to look for work. His mother was distraught. Arriving home one day, she found him on the couch again, watching reruns of Mystery Science Theater 3000. “Jesus, look at you,” she said. “If your father could see you, he’d be rolling over in his gravy!”

Why don’t turkeys get invited to high society parties?
Because the hosts are worried they’ll use fowl language.

An octogenarian calls his daughter a few days before Thanksgiving and tells her that he and her mother are getting a divorce. “But, daddy,” she says, “you can’t do that!” He explains that even though they’ve been together 50 years, they’re miserable and it’s for the best. “Please tell your brother and sister,” he says, “because I just don’t want to talk about it anymore.” The daughter immediately calls her siblings; they agree that they will not allow their parents to divorce. The daughter calls her father back. “There’s no way you’re getting a divorce,” she says. “We’re coming there tomorrow to sort this out. Don’t say anything to mom before we get there.” As she hangs up, her father turns to his wife and says, “It’s all taken care of, honey — they’re all coming for Thanksgiving, and it isn’t costing us a dime!”

November 25, 2010 at 12:45 am Leave a comment


I asked God for a good grade in math class, but I know God doesn’t work that way. So I cheated on my test and asked for forgiveness.

If you get depressed when you think about how dumb the average person is… then you’re probably horrified to realize that half the population is even dumber.

Light travels faster than sound, which is why some people appear bright until you hear them speak.

People who take a long time computing the ratio of rise to run are slope pokes.

Having gone to school doesn’t make you a teacher any more than standing in a garage makes you a car.

To steal ideas from one person is plagiarism. To steal from many is research.

I should’ve known things weren’t going to work out with my ex‑wife. After all, I’m an introverted mathematician, and she’s a lying, cheating, good‑for‑nothing whore.

Mathematicians don’t suffer from insanity. They enjoy every minute of it!

If Bill Gates had a penny for every time I had to reboot my computer — oh wait, he does.

November 23, 2010 at 8:29 am Leave a comment

Investigating National Pi Day

American Express is running ads for Small Business Saturday (November 27). It’s a good idea, but I was taken aback by one of their radio spots, which says:

There’s a day for everything — Thesaurus Day, Groundhog Day, National Pi Day…

That last one caught my ear. I’ve celebrated Pi Day for years, but National Pi Day? At first, I was sure the copywriters for American Express had screwed the pooch on this one. Pi Day cannot be a national holiday, because π is a universal constant. And the United States is not the only country that writes dates in the mm/dd format — so do Canada, Greece, Kenya, China, and the Phillipines, among others.

I did a little investigating. Sure enough, there is a National Pi Day. On March 12, 2009, the U.S. House of Representatives passed HRES 224, a non‑binding resolution that declares:

Whereas Pi can be approximated as 3.14, and thus March 14, 2009, is an appropriate day for “National Pi Day…”

The resolution continues:

The House of Representatives supports the designation of a “Pi Day” and its celebration around the world.

Doesn’t it seem a bit incongruous to declare a National Pi Day but then support its celebration around the world?

At least HRES 224 correctly states that π can be approximated as 3.14. This is in stark contrast to House Bill 246, passed by the Indiana State Legislature in 1897, which stated, among other things:

that the ratio of the diameter and circumference is as five-fourths to four

thereby implying that π = 16/5 = 3.2.

What a difference 113 years make, huh?

A geometry teacher hands a cylindrical metal container to a student and asks her to find the ratio of the circumference to the diameter. She thinks for a moment, then offers, “Um… pot pi?”

November 19, 2010 at 3:57 pm 2 comments

Mathematical Vick

It’s difficult to live inside the beltway and not cheer for the Washington Redskins. The cashier at the grocery store, the teller at the bank, and even the soft pretzel vendor at the corner of 7th and Independence — all of them are just a little friendlier after a Redskins victory. So even though I’ve been a Steelers fan since birth, I still root for the burgundy and gold, knowing that my reward will be better customer service the following day.

But this past Monday night, I found myself cheering against the Redskins and for Michael Vick. Are you kidding me? Six touchdowns — two running and four passing — with 333 passing yards, 80 rushing yards, and a 20-for-28 performance with 0 interceptions. Wow. With his effort, he set the record for most fantasy points ever earned by a quarterback.

His performance earned him a passer rating of 150.7, just shy of the perfect quarterback ranking of 158.3. Which brings me to a question — WTF? Since when has 158.3 ever been considered perfect? Why not just multiply the result by 100/158.3 and convert it to a 0‑100 scale? Or multiply by 28/158.3 to convert it to a 0‑28 scale, in which case the top score would be truly perfect?

Have you ever looked at the formula for passer rating in the NFL? What a mess. Here’s how it works:

Calculate a, b, c, and d as follows:

  • a = 5 × (completions/attempts – 0.3)
  • b = 0.25 × (yards/attempts – 3)
  • c = 20 × touchdowns/attempts
  • d = 2.375 – (25 × interceptions/attempts)

Then, the value of each of a, b, c, and d must be between 0 and 2.375. If the value is negative, use 0 instead; if it’s greater than 2.375, use 2.375. Finally, once you have the four values, the final passer rating is equal to:

100/6 × (a + b + c + d).

For Vick’s performance on Monday night, the calculations for a, b, c, and d look like this:

  • a = 5 × (20/28 – 0.3) = 2.071
  • b = 0.25 × (333/28 – 3) = 2.223
  • c = 20 × 4/28 = 2.857
  • d = 2.375 – (25 × 0/28) = 2.375

Note that c = 2.857 above, but because a, b, c, and d cannot exceed 2.375, a value of c = 2.375 is used in the final step. Consequently, his final passer rating was:

100/6 × (2.071 + 2.223 + 2.375 + 2.375) = 150.733,

which the media reports to the nearest tenth, 150.7.

There are some interesting questions that can be asked, based on the formula. For instance, to garner a perfect rating:

  • What percent of passes must be completed?
  • How many yards, on average, must be gained per pass attempt?
  • What percent of passes must result in a touchdown?
  • How many interceptions can be thrown?

(In case you want to think about these questions, answers are included at the bottom of the post.)

All of this football talk reminds me of a math joke…

A college football coach walked into the locker room before a big game, looked at his star quarterback, and said, “You’re academically ineligible because you failed your math mid-term. But we really need you today. I talked to your math professor, and he said that if you can answer just one question correctly, then you can play today. So, pay attention. I really need you to concentrate on the question I’m about to ask you.”

“Okay, coach,” the player agreed. “I’ll do my best.”

“Good,” said the coach. Then he asked, “Okay, now really focus. What is 2 + 2?” All of his teammates watched quietly while the quarterback thought about the question.

The quarterback thought for a moment. Sheepishly, he answered, “Um, 4?”

“Really?” said the coach. “Did you really just say 4?”

To which his teammates shouted, “Oh, c’mon, coach! Give him another chance!”

For a perfect passer rating of 158.3, a quarterback must do the following: 

  • Complete 31 of every 40 passes (77.5%).
  • Maintain at least 12.5 yards per attempt.
  • Score a touchdown on 19 of every 160 passes (11.875%).
  • Throw 0 interceptions.

November 18, 2010 at 11:56 am Leave a comment

Working at NCTM

I am the Online Projects Manager at the National Council of Teachers of Mathematics. I love my job — I’ve been here for 6 years, and I’ll stay here another 60, if they’ll let me; I love my organization — I’m not yet 40 years old, but I’ve been a member almost half my life; and I love my colleagues. But working at NCTM has its share of, um, challenges.

Take the equipment we have in the building, for instance. Today, I selected “single‑sided” on the photocopier, and all of my copies were printed on Möbius strips.

Of course, my mathy colleagues cause problems, too. There are three types of people who work at NCTM: those who can count, and those who can’t.

About a year ago, a small fire started in one of the hallways. An engineer, a scientist, and a statistician — who were at NCTM headquarters attending a summit about the merits of always including three related professions in the set-up of a joke — began debating the best way to extinguish the blaze.

“Dump some water on it!” the engineer suggested.

“No! Remove the oxygen!” said the scientist.

The statistician, however, started running around the building, starting fires in other locations. “What the heck are you doing?” the other two asked.

“Trying to create a decent sample size,” he said.

To put out the fires, a mathematician on staff brought them several buckets of water. The fires were extinguished one by one, but when they finished, there was an unused bucket of water. The statistician said to the mathematician, “Can you please get rid of that water?”

The mathematician proceeded to start another fire, and then he dumped the bucket of water on it.

“What’d you do that for?” the statistician asked.

“I reduced it to a previously solved problem,” said the mathematician.

More seriously, the following is a true story about NCTM.

The James D. Gates Building in Reston, VA, serves as the national headquarters for NCTM. In 1993, an addition to the building nearly doubled its size. In the area between the original structure and the addition, a courtyard was created, and a geometric design of circles and triangles was constructed on the floor of the courtyard with bricks and drainage pipes:

Long‑time members of NCTM might recognize the old NCTM logo:

Shortly after the building was expanded, however, it was learned that a number of publishing companies, eager to align themselves with NCTM after the release of Principles and Standards for School Mathematics, began placing the NCTM logo directly on their products. Cease‑and‑desist letters were sent to the publishers asking them to kindly remove the logo from their materials — and NCTM was shocked when they said, “No!” As it turns out, the publishers’ lawyers had done their homework, and they learned that the NCTM logo had never been trademarked. As a result, there was nothing that NCTM could do to prevent them from using it. 

Consequently, the NCTM logo was revised to the version we have today:


In the courtyard, we have a constant reminder of a bureaucratic blunder. As you’ll notice, the current logo has the ® symbol — and no one’s taken this one away from us, baby! Personally, I think the new one is better, anyway, with allusions to the infinity symbol; the letter x, as an algebraic variable; and a small child, which is a constant reminder that our profession is not just about numbers and shapes but about the lives we touch.

November 17, 2010 at 8:53 am Leave a comment

Notable and Quotable

Some of my favorite quotes by and about mathematicians:

I like your results. Let’s make it a joint paper, and I’ll write the next one. – Stefan Bergman

Someone told me that each equation that I included in the book would halve the sales. – Stephen Hawking

Amusement is one of the fields of applied mathematics. – W. F. White

The total number of Dirichlet’s publications is not large; jewels are not weighed in a grocery scale. – C. F. Gauss

Any astronomer can predict with absolute accuracy just where every star in the heavens will be at 11:30 tonight. He can make no such prediction about his teenage daughter. – J. T. Adams

November 14, 2010 at 8:24 am Leave a comment

Joy in Repetition

Today is 11/11, a day of repeated digits, which makes it a good day to share an email with you that I recently received. My coworker Julia blows me out of the water when it comes to being a number geek, and that’s saying something. Of course, her love of mathematics may be destiny — her name is Julia, and her brother’s name is Vitali. This is the message she sent me:

This Thursday, my dad will be 55 years old. On that same day, I’ll be 11,111 days old. It’s a day of repeated digits for [my] family.

I don’t know what compelled her to do the calculations that allowed her to figure that out, but it reminded me of some repdigit problems. I’ll share those in a minute. But first, a question about Julia:

How old was Julia’s dad when she was born?

Okay, that one was pretty easy. Here’s my favorite repdigit problem, which is a little tougher but can still be attempted by most anyone:

What is the smallest positive integer that, when multiplied by 7, gives a positive integer result in which every digit is a 5?

Of course, there’s the really cool repdigit number pattern:

1 × 1 = 1
11 × 11 = 121
111 × 111 = 12,321
1,111 × 1,111 = 1,234,321

Which leads to the question:

What is the value of the product 1,111,111,111 × 1,111,111,111?

And to end all this silliness, just some facts about repdigit polygonal numbers — numbers that repeat the same digit that are also polygonal numbers. Define P(k,n) to be the nth polygonal number with k objects on a side. For instance, P(3,4) = 10, because P(3,4) is the notation for the 4th triangular number (k = 3). Then P(5,4) = 22 is a repdigit polygonal number, and so is P(8,925,662,618,878,671; 387) = 666,666,666,666,666,666,666. Wow.

As it turns out, there’s a formula for these beasts:

P(k,n) = (n/2)(k – 2)(n – 1) + n  (for n, k > 1)

Over and over,
she said the words
’til he could take no more…

– Prince, Joy in Repetition

November 11, 2010 at 9:09 pm 4 comments

Theorems Without Thought

Conceptual understanding is overrated. It’s clearly better to teach rote algorithms without comprehension, so long as they can be repeated with minimal effort. Right?

I learned this poem a long time ago…

Ours is not to reason why;
Just invert and multiply!

But this one was new to me…

Minus times minus is equal to plus.
The reasons for this we need not discuss.

Here’s a limerick that provides the formula for a sphere without explanation…

A great circle inside a sphere
Has an area, it would appear,
Exactly one quarter —
Not longer or shorter —
Of that of the sphere. Is that clear?

And I really like this poem of a woman who doesn’t believe everything she’s told…

“Since day follows night,” they told Fawn,
“It is darkness that causes the dawn.”
But Fawn said her cat
Followed her, too, and that
Didn’t prove that the cat’s caused by Fawn.

November 10, 2010 at 12:02 am 1 comment

Race Results

In a race between two electric cars, one developed by a United States company, the other developed by a British firm, the American car prevailed. It was a friendly, unpublicized race, mainly giving each company a chance to test their cars on a closed course. Taking a page from Darrell Huff’s How to Lie with Statistics, however, a French newspaper ran the following headline:

In Race Between Electric Cars, British Car Loses,
and American Car Finishes Next‑to‑Last

November 9, 2010 at 7:58 am Leave a comment

Older Posts

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

November 2010

Enter your email address to subscribe to the MJ4MF blog and receive new posts via email.

Join 474 other followers

Visitor Locations

free counters