Martin Gardner puzzle: red, white, and blue weights

Here's a good puzzle from Martin Gardner's Mathematical Circus. The book is out of print but used copies are cheap.

Problems involving weights and balance scales have been popular during the past few decades. Here is an unusual one invented by Paul Curry, who is well known in conjuring circles as an amateur magician

You have six weights. One pair is red, one pair white, one pair blue. In each pair one weight is a trifle heavier than the other but otherwise appears to be exactly like its mate. The three heavier weights (one of each color) all weigh the same. This is also true of the three lighter weights. In two separate weighings on a balance scale, how can you identify which is the heavier weight of each pair?

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Interview with Adam Rubin, director of puzzles and games for The Art of Play

Our guest on the Cool Tools Show podcast this week is Adam Rubin. Adam is the New York Times best-selling author of Dragons Love Tacos, Robo-Sauce, and half a dozen other critically-acclaimed picture books. He is also a world-renowned inventor of illusions and was recently named Director of Puzzles and Games for

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Show notes:

Frixion Erasable Blue Gel Ink Pen ($13, 3 Pack) "So, this pen is not actually marketed as a disappearing ink pen. It’s marketed as a Frixion Pen, and its intention is to be an erasable pen — it’s a normal-looking pen and on the back of the pen is this sort of rubber or plastic nib. And if you write with the pen and you rub the nib over the ink, the ink goes away. But, the true nature of the pen is that it's heat activated. So, if you heat up the ink, it disappears. That could be with the nib that's on the back of the pen or that could be with the flame from a lighter or that could be in a microwave. So, basically, what you have, is you have a pen that writes with ink that you can make disappear with fire. And that is a pretty cool tool to me. … One of the cool things about it is that you can use it sort of as a fun science thing to do with kids because, you don’t necessarily need to use fire. Read the rest

Sphaera - a difficult dexterity puzzle

This puzzle designer, Fleb, has a YouTube channel that has in-depth videos of new and old puzzles. I love it. In this video, he tries out a puzzle called Sphaera, from Art of Play. Read the rest

This "simple" nail puzzle has kept me amused for hours

I was at Maker Faire Bay Area this weekend. One of my favorite things was a collection of simple handmade puzzles sitting on a table under an umbrella, away from the action. A Russian woman named Tatiana Ginzburg told me that the puzzles were part of some kind of mind enlightenment group she started. When I got back home I looked her up and found her website, Global Enlightenment.

I picked up the puzzle shown in the photo here. It's two nails, bent in such a way that the nails are linked. I spent about 15 minutes trying to disentangle them. I bought it for $10 and as I was walking away from the table, accidentally separated them. It took 15 minutes of trial and error to get them linked again. I spent the rest of Maker Faire fiddling with them. Every hour or so I was able to get them apart, but I didn't know how I did it. Last night when I got back home, I stayed up late and finally figured it out. I can get them unlinked in a few seconds. I still haven't figured out how to easily get them back together. I'll work on it tonight. I love this thing.

I don't know where you can buy this exact kind of nail puzzle. This one looks similar, though. Read the rest

Gallery of photos you might not immediately realize all include dildos

Subtle Dildo is a collection of photographs wherein dildos may be found by observant viewers. [via] Read the rest

Excellent $5 puzzle book: The Moscow Puzzles: 359 Mathematical Recreations

I bought the Dover edition The Moscow Puzzles in 2014, and it's still one of my all-time favorite puzzle books. Here are a few samples:

Book description:

This is, quite simply, the best and most popular puzzle book ever published in the Soviet Union. Since its first appearance in 1956 there have been eight editions as well as translations from the original Russian into Ukrainian, Estonian, Lettish, and Lithuanian. Almost a million copies of the Russian version alone have been sold.

Part of the reason for the book's success is its marvelously varied assortment of brainteasers ranging from simple "catch" riddles to difficult problems (none, however, requiring advanced mathematics). Many of the puzzles will be new to Western readers, while some familiar problems have been clothed in new forms. Often the puzzles are presented in the form of charming stories that provide non-Russian readers with valuable insights into contemporary Russian life and customs. In addition, Martin Gardner, former editor of the Mathematical Games Department, Scientific American, has clarified and simplified the book to make it as easy as possible for an English-reading public to understand and enjoy. He has been careful, moreover, to retain nearly all the freshness, warmth, and humor of the original.

Lavishly illustrated with over 400 clear diagrams and amusing sketches, this inexpensive edition of the first English translation will offer weeks or even months of stimulating entertainment. It belongs in the library of every puzzlist or lover of recreational mathematics.

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Can we wrap a 1x1x1 cube with the blue 3x3 piece of paper, cutting along some edges without disconnecting it?

Here's a good puzzle that Clifford Pickover found at CTK Insights:

Is it possible to wrap the cube with a 3×3 piece of paper below it? Handling of the paper is subject to two conditions:

1. The paper may be only cut or folded along the crease lines.

2. The cutting should not cause pieces to separate.

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Can you solve the virus riddle?

"Your research team has found a prehistoric virus preserved in the permafrost and isolated it for study. After a late night working, you’re just closing up the lab when a sudden earthquake hits and breaks all the sample vials. Will you be able to destroy the virus before the vents open and unleash a deadly airborne plague?"

A fun Ted-Ed puzzle by Lisa Winer.

[via] Read the rest

A hat puzzle

A good puzzle from our friends at Futility Closet:

Three logicians walk into a bar. Each is wearing a hat that’s either red or blue. Each logician knows that the hats were drawn from a set of three red and two blue hats; she doesn’t know the color of her own hat but can see those of her companions.

The waiter asks, “Do you know the color of your own hat?”

The first logician answers, “I do not know.”

The second logician answers, “I do not know.”

The third logician answers, “Yes.”

What is the color of the third logician’s hat?

Puzzle by MIT mathematician Tanya Khovanova. Click here for answer. Read the rest

This man is the master at making hedge mazes

Adrian Fisher is the master of making hedge mazes. He's designed more than 700 mazes in 40 countries. If Jack Torrance ever chases me, I'm calling Fisher for help.

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Five cool mass-market puzzles

Game design Fleb presents some of his favorite mass-produced puzzles. They are Hanayama Cast Cuby, Curvy Copter Cube, Iron Maiden. Red Dragon Egg, and the Hoberman Brain Twist. Read the rest

The Eureka disentanglement puzzle

The object of the Eureka puzzle is to remove the brass ring. As usual with Fleb's videos, there's a pause in the video if you don't want to see the solution. Read the rest

Make: Soviet themed launch-code box complete with missile switch covered toggles

Love puzzles, crypto, making, control panels and nuclear extinction? John Edgar Park has a maker project for you! Read the rest

Raymond Smullyan on the Tonight Show 1982

Here's puzzle master and logician Raymond Smullyan on the Tonight Show from 1982. It starts a bit awkwardly but gets good around the five minute mark. Smullyan died last week (I posted about it here).

[via] Read the rest

Puzzle: the lazy electrician

Here's a brain teaser from the Art of Play newsletter. I have not tried to solve it yet.

A lazy electrician is hired to fix the wiring in a tall building. In the basement are three buttons labeled, “A, B & C.” On the top floor of the building there are three ceiling fans in three different apartments labeled, “1, 2 & 3.” The landlord tells the electrician that each button in the basement is connected to one of the three fans upstairs—press the button once, and the fan turns on. Press it twice, and that same fan turns off. The problem is, no one knows which button controls which fan.

There is no elevator in the building and the electrician is very lazy so he will only climb up the stairs to the top floor once. It will take him nearly an hour to climb all the stairs and he refuses to use any assistance of any kind in order to complete this job. If it is impossible to see the fans from outside of their respective apartments, how does the electrician discover which button controls which fan once he climbs up the stairs for the first (and last) time?

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Interesting puzzles from the 2017 toy fair in Nuremberg, Germany

Tim from Grand Illusions shows off the neat puzzles he picked up at the 2017 toy fair in Nuremberg, Germany.

Every February, Tim visits the toy fair in Nuremberg, Germany. He is not sure if this was the 37th time or the 38th time! Anyway, Tim spends a number of days there, visiting every stand, searching out novel and entertaining items, both for his own toy collection, and also for the Grand Illusions Toy Shop.

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RIP Raymond Smullyan, Puzzle-Creating Logician

When I was in college I read and greatly enjoyed Raymond Smullyan logical puzzles books, especially What Is the Name of This Book? He died last week at the age of 97.

From the NYTimes:

Professor Smullyan was a serious mathematician, with the publications and the doctorate to prove it. But his greatest legacy may be the devilishly clever logic puzzles that he devised, presenting them in numerous books or just in casual conversation.

Sometimes they were one-offs, and sometimes they were embedded in longer narratives to explain mathematical concepts, such as Boolean logic, as he did in “The Magic Garden of George B and Other Logic Puzzles” in 2015; or retrograde analysis, as he explored in the “The Chess Mysteries of the Arabian Knights” in 1981.

He was also a character. With his long white hair and beard, Professor Smullyan resembled Ian McKellen’s wizard, Gandalf, from the “Lord of the Rings” film series. He was lanky, hated exercise and loved steak and eggs. He studied Eastern religion. He told corny jokes and performed close-up magic to anyone near him. He played the piano with passion and talent into his 90s. (A career in music had been derailed by tendinitis when he was a young man.)

Here are some of his puzzles. Read the rest

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