Puzzles

Long Range

A puzzler from Willis Ernest Johnson, Mathematical Geography, 1907:

“A man was forty rods due east of a bear, his gun would carry only thirty rods, yet with no change of position he shot and killed the bear. Where on earth were they?”

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The Missing Footmen

Like Nabokov, Lord Dunsany was fond of composing chess problems. This example was published in Hubert Phillips’ Week-end Problems Book of 1932:

dunsany - the missing footmen chess problem - 1

Two eccentric gentlemen abandoned this position at a chess club — White had announced mate in four. What was the mate?

The key is to notice that Black’s king and queen have changed positions. This is not possible if the black pawns are on their home squares. And this means that we’ve been viewing the position upside down:

dunsany - the missing footmen chess problem - 2

Now it’s clear that Black is hemmed in by his own pawns — White can mate him in four moves with the b8 knight, e.g. by 1. Nc6 Nf3 2. Nb4 (threatening Nd3#) Ne5 3. Qxe5 (any) 4. Nd3#.

Dunsany drew a game against Capablanca in a simultaneous exhibition in London in April 1929. He later wrote:

One art they say is of no use;
The mellow evenings spent at chess,
The thrill, the triumph, and the truce
To every care, are valueless.

And yet, if all whose hopes were set
On harming man played chess instead,
We should have cities standing yet
Which now are dust upon the dead.

Gender Issues

In a certain kingdom, boys and girls are born in strictly equal proportions. Determined to increase the proportion of women in the land, the sultan issues a decree: Any woman who bears a son is forbidden to have any further children. He reasons that some families will thus contain multiple daughters but a single son.

A number of years pass, and the sultan is confused to find that the kingdom still contains an equal number of boys and girls. Why?

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The Motor Hire

A puzzle from R.M. Abraham, Diversions & Pastimes, 1933:

Michael O’Bleary hired a motor-car at a cost of fifteen dollars to take him to Ballygoogly market and back again in the evening. When he got half-way on his outward journey he met a friend, gave him a lift to the market, and brought him back to the point where he picked him up in the morning. There was a dispute about the payment. How much should Michael charge his passenger for his share of the motor hire?

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Black and White

sam loyd chess puzzle 285

By Sam Loyd. White to mate in two.

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Truel

http://commons.wikimedia.org/wiki/File:Yevgeny_Onegin_by_Repin.jpg

You must participate in a three-way duel with two rivals. Each of you is given a pistol and unlimited ammunition. Unfortunately, you, Red, are the weakest shot — you hit your target only 1/3 of the time. Black is successful 2/3 of the time, and Gray hits everything he aims at.

It’s agreed that you will take turns: You’ll shoot first, then Black, then Gray, and you’ll continue in this order until one survivor remains. At whom should you shoot?

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Adding Up

What is the sum of all the figures in the numbers from 1 to 1 million?

Hint: With the right technique, this can be done in the head.

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Numbers Game

In 1938, Samuel Isaac Krieger of Chicago claimed he had disproved Fermat’s last theorem. He said he’d found a positive integer greater than 2 for which 1324n + 731n = 1961n was true — but he refused to disclose it.

A New York Times reporter quickly showed that Krieger must be mistaken. How?

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Suicide

loyd self-mate puzzle

By Sam Loyd. In how few moves can White force Black to mate him?

The answer is to castle queenside:

loyd self-mate puzzle solution

Now every Black move is mate.

Dotty

Each point in an infinite plane is colored either red or blue. Prove that there are two points of the same color that are exactly 1 meter apart.

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Don’t Shoot!

http://books.google.com/books?id=RolJAAAAYAAJ&printsec=frontcover&source=gbs_atb#v=onepage&q&f=false

The Schachfreund, edited by M. Alapin, gives the following amusing Chess Skit. A well-known chess master allowed weak opponents to make as many moves as they pleased during five minutes, as odds, before the beginning of a game, with the provision that they confined their moves to their own half of the board. At the end of the five minutes the game commenced, the odds-giver having the first move. During the five minutes one of them had played: [1. a4 2. Na3 3. h4 4. Nf3 5. d4 6. Nd2 7. Rh3 8. Nac4 9. Raa3 10. Ne4 11. Qd2 12. Rhf3 13. g3 14. Bh3 15. Qf4 16. Rae3], whereupon the odds-giver resigned without having made a single move, as he could not avoid mate in two.

The British Chess Magazine, January 1899

Sideline

In the 1890s an eminent Scot began to publish short popular science articles under an assumed name, for “the fun of seeing if he [could] make another reputation for himself.”

He succeeded, publishing three articles in the National Geographic before the secret leaked out.

The pseudonym was H.A. Largelamb. Who was the man?

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The Problem of the Calissons

A calisson is a flat French candy traditionally manufactured in the shape of two equilateral triangles joined along an edge. Suppose a quantity of these are packed randomly into a hexagonal container:

problem of the calissons

Each candy must take one of three orientations: east-west, northeast-southwest, or northwest-southeast.

As it happens, no matter how the candies are packed into the hexagon, an equal number will take each of these three orientations.

In the May 1989 issue of the American Mathematical Monthly, Guy David and Carlos Tomei demonstrated this with a beautifully intuitive “proof without words.” What had they seen?

Lincoln Seeks Equality

lincoln seeks equality puzzle

You’re in a pitch-dark room. On a table before you are 12 pennies. You know that 5 are heads up and 7 are tails up, but you don’t know which are which. By moving and flipping the coins you must produce two piles with an equal number of heads in each pile. How can you do this without seeing the coins?

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Straight and Narrow

http://commons.wikimedia.org/wiki/File:Monge_theorem.svg

Draw three nonintersecting circles of different sizes, and bracket each pair of them with tangents. Each pair of tangents will intersect in a point, and these three points will always lie along a line.

On being shown this theorem, Cornell engineering professor John Edson Sweet paused and said, “Yes, that is perfectly self-evident.” What intuitive proof had he seen?

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All’s Fair

Literary critic A.N. Wilson panned Bevis Hillier’s 1988 biography of John Betjeman. To get even, Hillier forged a love letter ostensibly written by Betjeman in 1944 and forwarded it to Wilson under the name Eve de Harben (an anagram for “Ever been had?”). Wilson took the bait and included the forged letter in his own biography of Betjeman, which was published in 2005.

Here’s the letter. It contains a hidden message — can you find it?

Darling Honor,

I loved yesterday. All day, I’ve thought of nothing else. No other love I’ve had means so much. Was it just an aberration on your part, or will you meet me at Mrs Holmes’s again — say on Saturday? I won’t be able to sleep until I have your answer.

Love has given me a miss for so long, and now this miracle has happened. Sex is a part of it, of course, but I have a Romaunt of the Rose feeling about it too. On Saturday we could have lunch at Fortt’s, then go back to Mrs. H’s. Never mind if you can’t make it then. I am free on Sunday too or Sunday week. Signal me tomorrow as to whether and when you can come.

Anthony Powell has written to me, and mentions you admiringly. Some of his comments about the Army are v funny. He’s somebody I’d like to know better when the war is over. I find his letters funnier than his books. Tinkerty-tonk, my darling. I pray I’ll hear from you tomorrow. If I don’t I’ll visit your office in a fake beard.

All love, JB

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Checkered Doughnuts

toroidal magic square - from mathematical circles

Roll this magic square into a tube by joining the upper and lower edges, then join the ends of the tube. Every row, column, and diagonal on the resulting torus will add to 34.

toroidal chess problem, from petrovic, mathematics and chess

Bend this chessboard similarly into a torus, then mate in 4.

Hint: The solution comprises only two lines.

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Disqualified

http://commons.wikimedia.org/wiki/File:Wendell_Willkie_presidential_campaign_poster_1940_crop.jpg

From Clark Kinnaird’s Encyclopedia of Puzzles and Pastimes, 1946:

Though a great American, Wendell Willkie nevertheless lacked one of the four necessary requirements for becoming President of the United States. One must be at least 35, a native-born American, and a resident of the U.S.A. for at least 14 years. Name the fourth requirement which Willkie also lacked?

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Roundup

Two old chestnuts:

1. I have six pieces of chain, each consisting of four links. It costs 10 cents to cut open one link and 25 cents to weld it together again. What will it cost to have the six pieces joined into one chain?

2. The two volumes of my scintillating autobiography stand side by side in order on a shelf. A bookworm starts at page 1 of volume 1 and eats his way in a straight line to the last page of volume 2. If each cover is 1/8 of an inch thick, and each book without the covers is 2 inches thick, how far does the bookworm travel?

And two trick questions:

1. What is the name of the title character in The Merchant of Venice?

2. Who played Frankenstein in the 1931 American film?

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Murder in the Attic

a.c. white chess puzzle

By A.C. White. Mate in 12.

Hint: It’s vastly easier than it sounds.

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Thin Thinking

http://commons.wikimedia.org/wiki/File:San_Juan_Bautista_El_Greco.jpg

Some of the figures (particularly the holy ones) in El Greco paintings seem unnaturally tall and thin. An ophthalmologist surmised that the painter had a defect of vision that caused him to see people this way.

The zoologist Sir Peter Medawar pointed out that we can reject this conjecture on purely logical grounds. What was his insight?

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On Target

Samuel Isaac Jones offered this poser in his 1929 book Mathematical Wrinkles:

Cook was within 10 miles of the north pole and Peary was also within 10 miles of the pole, but 20 miles from Cook. What direction was Peary from Cook? Suppose Peary threw a ball at Cook and hit him. In what direction did the ball go?

He omitted the answer, apparently inadvertently. What is it?

A Missed Opportunity

bruno sommer missed opportunity

By Bruno Sommer, 1910. White has just moved, and he realizes too late that he could have mated Black on the move. What was his last move, and what was the mate?

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The Crossing

A family of four has to cross a river. The father and mother each weigh 150 pounds, and each of the two sons weighs 75 pounds. Unfortunately, the boat will carry only 150 pounds maximum. How can they get across?

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