Posts tagged ‘NPR’

Number Challenge from Will Shortz and NPR

Typically, the NPR Sunday Puzzle involves a word-based challenge, but this week’s challenge was a number puzzle.

[This challenge] comes from Zack Guido, who’s the author of the book Of Course! The Greatest Collection of Riddles & Brain Teasers for Expanding Your Mind. Write down the equation

65 – 43 = 21

You’ll notice that this is not correct. 65 minus 43 equals 22, not 21. The object is to move exactly two of the digits to create a correct equation. There is no trick in the puzzle’s wording. In the answer, the minus and equal signs do not move.

Seemed like an appropriate one to share with the MJ4MF audience. Enjoy!


October 18, 2017 at 8:07 am Leave a comment


In case you missed it, the following mathy challenge was presented by Will Shortz as the NPR Sunday Puzzle on February 28:

Find two eight-letter terms from math that are anagrams of one another. One is a term from geometry; the other is from calculus. What are the two words?

Will ShortzThe irony of this puzzle (for me) appearing on that particular Sunday is that five days later, I delivered the keynote presentation for the Virginia Council of Teachers of Mathematics annual conference, and I had included the answer to this puzzle as one of my slides. I wasn’t trying to present an answer to the NPR Puzzle; I was merely showing the two words as an example of an anagram. The following week, Will Shortz presented the answer as part of the NPR Sunday Puzzle on March 6.

Slide from My Presentation
(aka, the answer)

What I particularly enjoyed about the March 6 segment was the on-air puzzle presented by Shortz. He’d give a category, and you’d then have to name something in the category starting with each of the letters W, I, N, D, and S.

I’ve always heard that good teachers borrow, great teachers steal. So I am going to blatantly pilfer Shortz’s idea, then give it a mathy twist.

I’ll give you a series of categories. For each one, name something in that category starting with each of the letters of M, A, T, and H. For instance, if the category were State Capitals, then you might answer Madison, Atlanta, Topeka, and Harrisburg. Any answer that works is fine. But for many of the categories, you’ll earn bonus points for mathy variations. For instance, if the bonus rule were “+1 for each state capital that has the same number of letters as its state,” then you’d get two points for Atlanta (Georgia) and Topeka (Kansas), but only one point for Madison (Wisconsin) and Harrisburg (Pennsylvania).

There are nine categories listed below, and the maximum possible score if all bonuses were earned would be 79 points. I’ve listed my best answers at the bottom of this post, which yielded a score of 62 points. Can you beat it? Post your score in the comments.

Want to play this game with friends or students?
Download the PDF version.


Movie Titles
(+1 for a math movie)
M _____
A _____
T _____
H _____

Historical Figures
(+1 if the person is a mathematician or scientist)
M _____
A _____
T _____
H _____

(+1 if the game is mathematical)
M _____
A _____
T _____
H _____

School Subjects
(+1 for mathematical subjects)
M _____
A _____
T _____
H _____

Words with One-Word Anagrams
(+1 if it’s a math term)
M _____
A _____
T _____
H _____

Words Containing the Letter “Q”
(+1 if it’s a math term)
M _____
A _____
T _____
H _____

Math Terms
(+3 if all four terms are related, loosely defined as “could be found in the same chapter of a math book”)
M _____
A _____
T _____
H _____

Words Containing the Letters M, A, T, and H
(+1 if the letters appear in order, though not necessarily consecutively; +2 if consecutive)
M _____
A _____
T _____
H _____

Words with a Single-Digit Number Word Inside Them
(such as asinine, but -1 if the number word is actually used numerically, such as fourths; +2 if the single-digit number is split across two or more syllables)
M _____
A _____
T _____
H _____


The following are my answers for each category.

Movie Titles
Moebius, Antonia’s Line, Travelling Salesman, (A) Hill on the Dark Side of the Moon
(8 points)

Historical Figures
Mandelbrot, Archimedes, Turing, Hypatia
(4 points)

Mancala, Angels and Devils, Tic-Tac-Toe, Hex
(8 points)

School Subjects
Mathematics, Algebra, Trigonometry, History
(7 points)

Words with One-Word Anagrams
mode (dome), angle (glean), triangle (integral), heptagon (pathogen)
(8 points)

Words Containing the Letter “Q”
manque, aliquot, triquetrous, harlequin
(6 points)

Math Terms
median, altitude, triangle, hypotenuse
(7 points)

Words Containing the Letters M, A, T, and H
tch, aromatherapy, thematic, homeopathic
(8 points)

Words with a Single-Digit Number Word Inside Them
mezzanine, artwork, tone, height
(6 points)

March 25, 2016 at 1:46 pm Leave a comment

NPR Puzzle Combinations

During yesterday’s NPR Sunday Puzzle, puzzlemaster Will Shortz presented the following challenge:

I’m going to give you some five-letter words. For each one, change the middle letter to two new letters to get a familiar six-letter word. For example, if I said FROND, F-R-O-N-D, you’d say FRIEND, because you’d change the O in the middle to I-E.

He then presented these nine words:


You can figure out the answers for yourself. For those that give you real trouble, you can either listen to the broadcast or search for the answer at More Words.

For those of you who don’t know who Will Shortz is, you have something in common with detective Jake Peralta from Brooklyn Nine-Nine:

The puzzle was fun. But what was more fun was the conversation that our family had about it. After the third word, Alex announced, “This shouldn’t be that hard. There are only 676 possible combinations.”

What he meant is that there are 26 × 26 = 676 possible two-letter combinations, which is true.

He continued, “But you can probably stop at 675, because Z-Z is pretty unlikely.”

I smiled. He had chosen to exclude Z-Z but not Q-K or J-X or V-P.

Yet his statement struck me as a challenge. Is there a five-letter word where the middle letter could be replaced by Z-Z to make a six-letter word? Indeed, there are several:


None of them are perfect, though, because Z-Z is not a unique answer. For instance, ROVER could become ROBBER, ROCKER, ROMPER, ROSTER, or ROUTER, and most puzzle solvers would surely think of one of those words before arriving at ROZZER (British slang for a police officer).

From the list above, the best option is probably GUILE, for two reasons. First, stumbling upon GUZZLE as the answer seems at least as likely as the alternatives GUGGLE, GURGLE, and GUTTLE. Second, the five-letter hint has only one syllable, but the answer has two, and such a shift makes the puzzle just a little more difficult.

But while Alex had reduced the field of possibilities to 675, the truth is that the number was even lower. The puzzle states that one letter should be “changed to two new letters,” which implies that there are only 25 × 25 = 625 possibilities. Although that cuts the number by 7.5%, it doesn’t help much… no one wants to check all of them one-by-one to find the answer.

When Will Shortz presented DEITY, the on-air contestant was stumped. So Will provided some help:

I’ll give you a tiny, tiny hint. The two letters are consonant, vowel.

Alex scrunched up his brow. “That’s not much of a hint,” he declared.

Ah, but it is — if you’re using brute force. To check every possibility, this reduces the number from 625 to just 21 × 5 = 105, which is an 80% reduction.

Still, Alex is correct. The heuristic for solving this type of puzzle is not to check every possibility. Rather, it’s to think of the word as DE _ _ TY, and then check your mental dictionary for words that fit the pattern. It may help to know that the answer isn’t two consonants, but most puzzle solvers would have suspected as much from the outset. In the English language, only SOVEREIGNTY, THIRSTY, and BLOODTHIRSTY end with two consonants followed by TY.

Below are five-letter math words for which the middle letter can be changed to two new letters to form a six-letter word. (Note that the answers aren’t necessarily mathy.)

DIGIT :: DI _ _ IT (unique)

POINT :: PO _ _ NT

FOCUS :: FO _ _ US

MODEL :: MO _ _ EL (unique)

POWER :: PO _ _ ER

RANGE :: RA _ _ GE (unique)

SOLID :: SO _ _ ID (unique)

SPEED :: SP _ _ ED

And below, your challenge is reversed: Find the five-letter word that was changed to form a six-letter math word.

CO _ EX :: CONVEX (unique)

LI _ AR :: LINEAR (unique)


RA _ AN :: RADIAN (unique)




December 8, 2015 at 6:20 am Leave a comment

Wait, Wait… I’ve Got a Math Question

Wait Wait“Not My Job” is a segment on the NPR game show Wait, Wait… Don’t Tell Me! During the segment, host Peter Sagal asks a celebrity three questions, on a topic about which they likely have no clue. For instance,

  • Cindy Crawford was asked questions about scale models, not supermodels;
  • Rob Lowe was asked questions about bratwurst, not the Brat Pack;
  • Stephen King was asked questions about the Teletubbies; and,
  • Leonard Nimoy was asked questions about the other Dr. Spock (you know, the celebrity pediatrician).

Will OldhamMy favorite of these segments, however, was with singer-songwriter Will Oldham, better known by his stage name Bonnie “Prince” Billy. Sagal explained, “You sing mostly sad or mournful songs, interspersed with the occasional tragic one. And we were thinking, who’s the singer least like you? […] So, we’re going to ask you three questions about Ms. Doris Day, the sweet-faced, sweet-voiced singer most famous in the 50s and 60s.”

Oldham answered two of the three questions correctly, so he won.

As Sagal congratulated him, Oldham pretended that Doris Day was in the room with him. “Hey, Doris, you were right!” he said. “All the questions were about you!”

Now, that’s funny!

(As an aside, let me share with you a slide that I sometimes show during presentations about classroom technology:

Technology - Doris Day

Yep, that’s Doris Day in the 1958 movie Teacher’s Pet. Hopefully that image looks a little odd to you in 2015. Honestly, if you’re teaching math to adolescents and still using chalk and a wooden pointer, I’ll kindly ask you to consider a different career. There are other options for you. For instance, you could become a dentist and specialize in square root canals. But, I digress.)

So, back to the point.

The celebrity quiz contains three multiple-choice questions, each with three choices. If the guest answers at least two questions correctly, he or she wins. Which got me to thinking…

What is the probability that a celebrity guest will get at least two questions correct if she guesses randomly?

Brute force is definitely an option here. Write down all possible answer choice combinations, randomly decide which configuration will be correct, and then figure out how many of the possible combinations would yield a winner. Not pretty, but it works.

Speaking of combinations, here’s a joke that just has to be shared:

Combinatorial Pillow Talk

Courtney Gibbons’s comics used to appear at Brown Sharpie, but then she got a job.

November 11, 2015 at 9:36 pm Leave a comment

Word + Letter = Math Term

AnagramOn a recent Sunday Puzzle on NPR, Will Shortz gave a letter and a word, and the contestant was to guess the name of a popular TV show using an anagram of the letters (“Coming to TV This Fall: Anagrams,” Oct 12, 2014). For instance,


gave the answer


This struck me as an interesting puzzle format. My only criticism is that it just wasn’t mathy enough.

But I’m not a problem maker, I’m a problem solver… so rather than cast aspersions at the puzzle, I’ll instead use the format to offer my own version.

Each of the 26 letters of the alphabet has been paired with a common English word. An anagram of the pair will yield a common math word. How many can you find?

  1. A + ERA
  2. B + AGLARE
  3. C + BITES
  4. D + NOTICER
  5. E + EDGERS
  6. F + SAUCER
  7. G + LEAN
  9. I + TANGLER
  11. K + SEW
  12. L + POSE
  13. M + RIPS
  14. N + AIMED
  15. O + PINT
  16. P + MYRIAD
  17. Q + AURES
  18. R + ENVIES
  19. S + RECITED
  20. T + HAM
  21. U + RAIDS
  22. V + EXERT
  23. W + ROPE
  24. X + SEA
  26. Z + ORE

I don’t believe in providing an answer key, but you can find some help at Math Words, and you can click over to More Words if you run into real trouble. But give it the old college try before seeking assistance. Honestly, you’ll feel better about yourself if you solve these on your own.

October 31, 2014 at 7:10 am Leave a comment

Garrison Keillor Reads Math Poem

As Garrison Keillor said, “Here’s a poem for today by Mary Cornish, entitled Numbers.” (Or maybe you’d prefer to hear GK read the poem on The Writer’s Almanac.)

Numbers, by Mary Cornish

I like the generosity of numbers.
The way, for example,
they are willing to count
anything or anyone:
two pickles, one door to the room,
eight dancers dressed as swans.
I like the domesticity of addition—
add two cups of milk and stir
the sense of plenty: six plums
on the ground, three more
falling from the tree.

And multiplication’s school
of fish times fish,
whose silver bodies breed
beneath the shadow
of a boat.

Even subtraction is never loss,
just addition somewhere else:
five sparrows take away two,
the two in someone else’s
garden now.

There’s an amplitude to long division,
as it opens Chinese take-out
box by paper box,
inside every folded cookie
a new fortune.

And I never fail to be surprised
by the gift of an odd remainder,
footloose at the end:
forty-seven divided by eleven equals four,
with three remaining.

Three boys beyond their mothers’ call,
two Italians off to the sea,
one sock that isn’t anywhere you look.

June 5, 2012 at 3:32 pm 1 comment

More Number Picking

In a previous post, I mentioned the Pick-a-Number game that the folks at NPR’s Planet Money were running:

Pick a number between 0 and 100. The goal is to pick the number that’s closest to half the average of all guesses. For example, if the average of all guesses were 80, the winning number would be 40.

If everyone picked randomly, you would expect the mean to be approximately 50, in which case the winning number would be 25. So, you’d choose 25, right? But if everyone uses that same logic, then the mean would be 25, and the winning number would be 12.5. So, you’d choose 12.5, right? But if everyone used that same logic…

Well, you get the point.

When making your choice, it starts to feel like a game against Vizzini, the Sicilian from Princess Bride.

Only a great fool would reach for what he was given. I am not a great fool, so I can clearly not choose half the expected mean. But you must have known I was not a great fool, so I can clearly not choose half of half the expected mean…

Well, the results are in, and you can view them (and an explanation) here.

I take a minimal level of pride in receiving one of 772 honorable mentions for my guess of 12. (Don’t look for my name in the list, though. I used my son’s name as a pseudonym.)

Here’s a very simple pick-a-number game:

Pick a number between 12 and 5.

Make your pick before reading the next paragraph.

Did you pick 7? Most people do. My theory is that the magnitude and order of the numbers matters. Because the larger number is given first, and because the difference between the numbers falls within the appropriate range (12 – 5 = 7), it’s the “obvious” choice.

The trick would probably work equally well if the set-up were, “Pick a number between 19 and 6.” I suspect the most common choice would be 13.

Of course, this is just pop math psychology.

Speaking of “picking” and “numbers,” here’s a line a friend of mine used on an attractive waitress:

How can it be it that I’ve memorized the first 100 digits of π, yet I don’t know the 7 digits in your phone number?

For the record, I condone neither hitting on a waitress nor using that line.

October 17, 2011 at 9:50 am Leave a comment

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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.

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