Showing posts with label logical games. Show all posts

Thursday, February 12, 2015

Napoleon's Star

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Napoleon had an obsession: a star. His star. He would talk about it to everyone, and whoever would listen to him out of respect, would point at the star in the sky. Napoleon even talked about the star during the Russian campaign, while his troops were receding.

It seems like Talleyrand sent him the game - Napoleon's Star - on the evening of 17th June, 1815, the day before the Battle of Waterloo. It has been said that the great general spent the entire night and the following day, until sunset, trying to solve the game, without hearing the noise of the battle and without listening to his officers pleading for help. When he came out of his tent to breath some fresh air, looking tired and unshaven, but with the solution in his grasp, Waterloo had already been won by the English, and his troops were fleeing with no order or hope.

napoleon star

Here's the game: start from any of the ten points, marked with a letter, and follow - in a staight line - to the third point from the starting position (eg from a to g); place a coin on this third point. Then pick another point unoccupied by any coin, and again go to a third unoccupied point in a straight line (a coin on the second point doesn't matter), and place a coin on it. Repeat the procedure until you've placed nine coins.

Napoleon's Star Puzzle Solution

To be able to place nine coins, it is necessary to make the 3rd point of each step equal to the start point of the previous step. For example:

a-g; i-a; c-i; f-c; e-f; h-e; b-h; j-b; d-j.

napoleon star soution

 With such a simple solution, it's hard to believe that Napoleon stayed in charge for so long.

Saturday, February 7, 2015

Southern Cross

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There is a missing number in the table below.
4 5 6 7 8 9
61 52 63 94 46

What number goes in the blank box?

Southern Cross Puzzle Solution

The missing number is 18. The numbers in the bottom row are the square of the numbers in the top row, but with their digits reversed.
4 5 6 7 8 9
61 52 63 94 46 18

Wednesday, January 28, 2015


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There is a number made of eleven tens of thousands, eleven thousands, eleven hundreds, and eleven units?

What is that number?

Canopus Puzzle Solution

A nice and simple sum does the trick.…
110,000 +
11,000 +
1,100 +
11 =

Tuesday, January 13, 2015

Visit At The Kremlin

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"This," explained Colonel Nevskij to the Druggar of Bongo Ghango - chief of a large country by River Ghango - "is the Buttons Room."

"I've seen a room like this in Washington," replied the big Chief, smiling with satisfaction, "there too, you couldn't see a single button. The only ones I can see here are, uh.. hehe, the ones on your uniform, Colonel!"

"Ahah, comrade Druggar likes joking. But the buttons are here," replied the Soviet, pointing at a large panel at the end of the room, "they are behind that panel."

"A very large panel," observed the Chief, "much larger than the one at the White House: I presume there are more buttons here."

"Of course, comrade Druggar: in America, only a bunch of opportunistic capitalists has a saying in the big decisions, while here, uh, here is different: the entire Soviet community, through its representatives, takes part in the decision process of the Union."

"Any citizen could then come here and press the buttons?"

"Err, no, not exactly. If I tried to do it, the room would fill up with narcotic gas, an alarm would set off, and... Well, no need to talk about that. For each button there is a slot, into which a magnetic card must be inserted, to activate the corresponding button. Therefore, no card, no button. To launch the missiles, every button must be activated and pressed, and only a handful of comrades holds the magnetic cards, which of course, each of them has a different code from the others. The personalities holding the cards are the Secretary of the Communist Party, the President of the Praesidium, the Chief of the KGB, and five comrades, Heroes of the Soviet Union. The distribution - and here is the originality of our system - is such that the Secretary of the Party holds the complete set of codes, and so he can launch the missiles by himself; if the Secretary is not available, the missiles can be launched by the President of the Praesidium together with the Chief of the KGB, or by anyone of these two, together with any two of the five Heroes of the Union. If - Marx forbid - the Secretary, the President, and the Chief have all been victimised by an imperialistic attack, our nuclear response can be initiated by any four of the five Heroes of the Soviet Union; any four of them would be sufficient to have the entire set of magnetic cards to activate the buttons."

"So, how many buttons are there?" asked the Chief.

What is the minimum number of buttons, and how are they distributed?

Visit At The Kremlin Puzzle Solution

There are 20 buttons. This is because there are 10 combinations of Heroes in pairs of 2, and this is multiplied by 2 because these combinations have to be mapped to two different persons (the President of the Praesidium or the Chief of KGB). The magnetic cards, as held by the eight persons, and marked with an X, are distributed as follows:
Person Buttons
Secretary of Party X X X X X X X X X X X X X X X X X X X X
President of Praesidium X X X X X X X X X X X X X X X - - - - -
Chief of KGB - - - - - X X X X X X X X X X X X X X X
1st Hero X X X X - - - - - - - X X X X X X X X -
2nd Hero X X X - X X X X - - - - - - X X X X - X
3rd Hero X X - X X - - X - X X - - X - X X - X X
4th Hero X - X X X - X - X - X - X - - X - X X X
5th Hero - X X X X X - - X X - X - - - - X X X X

Wednesday, December 24, 2014

A Law-Abiding Citizen

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"Where do you think you're going with that thing?" asked the bus driver.

"Where do you think I'm going? On this bus, of course. Why, can't I?" replied the electrician.

"No, of course you can't," said the bus driver in a very patronising way. "It is forbidden to bring any object of length, width, or height greater than one metre on any bus. That thing you're carrying is longer than one metre."

"It's got nothing to do with a ticket," screeched the driver. "You could buy a dozen tickets, and I still would not let you ride on this bus!"

Irritation grew rapidly within the electrician. "Listen! I need to take this neon light tube to a ceremony. I don't have a car. The cabbies are on strike. And it's raining. What do you expect me to do!"

"I don't know, and I don't care anyway. You ain't gonna come on this bus with that tube. End of story."

Quickly, the electrician dashed into a shop next to the bus stop and came out with a package containing the neon tube. Smugly, with all thirty-two teeth on display, he showed the package to the bus driver. "Now can I come on the bus?"

With a snort, the bus driver pulled out a folding rule and performed a precise measurement. Scowling, he waved in the smug commuter.

How did the electrician manage to pack a 1.2 metre neon tube into a package less than one metre?

A Law-Abiding Citizen Puzzle Solution

The electrician packed the tube diagonally into a flat-ish squared package, with sides of less than one metre. More precisely, the sides were about 0.85 metres long, because [squareroot(1.2² / 2) = 0.84852...]

Friday, December 19, 2014

Tamerlano's Trap II

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Alvise Moschin, a Venetian merchant, was dragged into the Hazel Room of Samarcanda Palacethe by a pair of soldiers. Although fairly worried, Moschin felt some confidence due to his knowledge of the East. He knew, through tales heard in wine bars, what was waiting for him and how he should react. For a start, he would find himself in front of two doors guarded by two soldiers, a liar and and truth-teller. That would not be a problem.

The street-smart Venetian was thrown onto the rug before a throne. Despite his predicament, he could not contain a grin, which only widened when he saw Tamerlano enter the room and take a seat upon the throne before him.

"Get up, merchant!" barked the conqueror. "There are two doors behind you--"

"Behind one of them there's a horse, and behind the other there are crocodiles, am I right?" interrupted the merchant.

Tamerlano leaned back. "You are smart and well informed, christian," he said. "However, this time we'll have a slight variation. You will not find two guards, but one. He will be the one to whom you may ask the single question. From that, you must decide which door will lead you to certain death and which to freedom. Also, you will not know whether he always lies or always tells the truth."

With his face pale, as if he had seen a ghost, Moschin turned around and saw that between the two doors, there was indeed only one guard. The guard bore a satanic grin, his piercing eyes staring. Moschin approached the guard slowly, his mind working frantically...

What question must Alvise Moschin ask to determine which is the door to freedom?

Tamerlano's Trap II Puzzle Solution

Moschin asked the guard: "If I had asked you which door leads to freedom, which door would you have pointed me to?"

If the guard was truthful, he would have shown the right door. If he lies, he would have again shown the right door, because he would have given the merchant the opposite answer to what he would have given if he was asked a direct question.

Thursday, December 4, 2014


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hydra jigsaw puzzle

A team of four girls and six boys put together a 2200-piece jigsaw puzzle in 4 hours. The same jigsaw puzzle was put together in 8 hours by a team of two boys and five girls.

Who are better at putting jigsaw puzzles together, boys or girls?

Hydra Puzzle Solution

If 6 boys and 4 girls spend 4 hours to complete the jigsaw puzzle, then 3 boys and 2 girls will need 8 hours, which is also the amount of time needed by the team of 2 boys and 5 girls. The reader can see that the input of 1 extra boy on the first team equals the input of 3 extra girls on the other team. The conclusion deduced is that the input from 1 boy is worth as much as the input from 3 girls.

To be more precise, it is possible to demonstate that each boy can put together, in one hour, 75 pieces of the puzzle, compared to the 25 for each girl. This is because, if we say that 6 boys and 4 girls (ie team 1) are equal to 22 girls ((6 * 3) + 4), and since that team puts together 550 pieces per hour (2200 / 4), then the workforce of each team member equals 25 pieces/hour (550 / 22).

Sorry ladies about the "non politically correct" nature of this puzzle, but I'm just translating. I was actually thinking of using Martians and Venusians instead, but then I thought "Who cares!" - Mickey.

Monday, November 24, 2014

Top Secret

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With his heart rate increasing steadily, James Bents (alias Lt-Colonel Ivanovic Zdanov, as far as the KGB were concerned) lined up behind the scientists who were walking towards the internal gate. Thanks to his forged documentation, he was able to pass through the two previous gates. He was aware that to get right inside the missile launch-pad, he would need to supply a password. He had been informed that the password changed daily. Only his extreme cool and many years of training enabled him to contain the fear.

The two scientists in front of him reached the gate, which was patrolled by machine-gun wielding soldiers. He strained to hear the voices of the people ahead of him in the queue.

"Twelve?" asked the guard.

"Six," replied the first scientist.

The first scientist strode through the gate as the second one walked to the guard.

"Six?" asked the guard.

"Three," replied the second scientist and walked through.

Relief and confidience spread through Bents; the method that drove questions and answers was trivial. He stepped forward.

"Nine?" asked the guard.

Brents hesitated for a split second. This was an unpredicted complication, but his arduous conditioning allowed the secret agent to remain calm and as sharp as a razorblade. "Four and a half," he answered without blinking.

Quite suddenly, the entire area was filled with floodlights. Alarm sirens broke the silence of the otherwise peaceful night. In a fraction of a second the Lt-Colonel realised his mistake. He tried to turn on his heels and run, but instantly felt the cold barrel of a machine-gun pressed against his neck.

What was the secret agent's fatal mistake?

Top Secret Puzzle Solution

The answers given were the the number of letters in the question. When asked "Nine?" the secret agent should have answered "Four".

Friday, November 14, 2014

A Struggle For Survival

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"There are only two planets in this solar system that would offer a chance of survival to a Gxz," the geoanthropologist told the commander of the starship after having examined the data from the probe. "They are the sixth one from the sun and the eight one towards the sun."

The commander turned towards the astronavigator. "Current position?"

The navigator moved his tentacles quickly on the keyboard, "We are approaching one of the three orbits that are between the two mentioned by the anthropologist; the most internal one of the three, to be precise."

"What is this planet like," the commander asked.

"Uninhabitable," replied the geoantropologist. "The atmosphere is full of lethal gases such as oxygen. Gravity is moderate, and there's bucketloads of a mixture of hydrogen and oxygen without any silicon whatsoever; just thinking about it makes my verrucas crawl!"

"How many planets in this solar system?" asked the commander.

"Less than 12," the astrophysicist replied, peering at the instruments. "The exact number is..."

That's the end of the commander's log, found within the wreckage of the starship, and painstakingly translated. How many planets did that solar system contain?

a solar system

A Struggle For Survival Puzzle Solution

The answer is nine planets. The geoanthropologist states that one of the habitable planets is eighth toward the sun, so there must be at least 8 planets. The navigator mentions that there are 3 planets between the 6th planet and the 8th towards the sun. The only number that can satisfy both statements is the number nine. You will then realise that the navigator was talking about Earth.

Tuesday, November 4, 2014

A Thinking Man

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Professor Percent was a maths lecturer with an interest for new ways to express mathematical expressions. The traditional symbols (+, -, *, /, etc) were not enough anymore, to convey his superior numeric operations, so he had to invent new symbols, and only a superior brain would be able to understand the need for his new symbols.

The first symbol he invented was §; between two numbers, it meant that, if the first number was greater than the second, then the second should be subtracted from the first one; otherwise the two numbers should be added. Therefore 5 § 2 = 3, while 2 § 5 = 7.

The poor people that had to put up with this were, of course, his students. In the last test they were faced with:

5 ¿ 2 = 27
6 ¿ 3 = 27
8 ¿ 4 = 36

and also with:
5 ¤ 2 = 15
6 ¤ 4 = 12
3 ¤ 8 = 40

What are the meanings of the symbols ¿ and ¤?


There are at least 3 different solutions for ¿.

A Thinking Man Puzzle Solution

The symbol ¿ means the difference between the number made up of the all digits of the operation, and the mirror of this last number. i.e,
5 ¿ 2 = 52 - 25 = 27
6 ¿ 3 = 63 - 36 = 27
8 ¿ 4 = 84 - 48 = 36

An alternative solution for this symbol (submitted by Alfa Chan... many thanks!) is simply the difference between the two numbers multiplied by 9. i.e,
5 ¿ 2 = (5 - 2) × 9 = 27
6 ¿ 3 = (6 - 3) × 9 = 27
8 ¿ 4 = (8 - 4) × 9 = 36

Another alternative solution submitted by Mickey Kawick... thanks!! We have x ¿ y; If x is odd, then the result is 5x + y, otherwise it's 5x - y. i.e,
5 ¿ 2 = 5 × 5 + 2 = 27 (5 is odd, so we add the 2)
6 ¿ 3 = 6 × 5 - 3 = 27 (6 is even, so we subtract the 3)
8 ¿ 4 = 8 × 5 - 4 = 36 (8 is even, so we subtract the 4)

The symbol ¤ means the difference between the two numbers multiplied by the larger of the two numbers. i.e,
5 ¤ 2 = (5 - 2) * 5 = 3 * 5 = 15
6 ¤ 4 = (6 - 4) * 6 = 2 * 6 = 12
3 ¤ 8 = (8 - 3) * 8 = 5 * 8 = 40

An alternative solution for this symbol, as submitted by Jeff Schall (many thanks!), is the difference between the square of the bigger of the two numbers and their product. i.e,
5 ¤ 2 = (5 ^ 2) - (5 * 2) = 25 - 10 = 15
6 ¤ 4 = (6 ^ 2) - (6 * 4) = 36 - 24 = 12
3 ¤ 8 = (8 ^ 2) - (3 * 8) = 64 - 24 = 40

Saturday, October 25, 2014

Barrels 'O' Fun

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In the basement of the Italian "cantina", there are 3 small, irregularly-shaped, wine barrels: a 12-litre one, full, and two empty ones, which can contain up to 7 and 5 litres.

Without using any additional tool, how can you get exactly 6 litres of wine in the 7-litre barrel, and have 6 litres left in the 12-litre barrel?

Barrels 'O' Fun Puzzle Solution

There are multiple ways of solving this. One way is given below, and it's probably the fastest one. Each set of 3 numbers separated by hyphens is the amount of wine (in litres) in the 3 barrels after each "pouring operation". The 3 barrels are always in the same order: 12, 7, and 5 litres.
  • 12-0-0
  • 5-7-0
  • 5-2-5
  • 10-2-0
  • 10-0-2
  • 3-7-2
  • 3-4-5
  • 8-4-0
  • 8-0-4
  • 1-7-4
  • 1-6-5
  • 6-6-0.

Monday, October 20, 2014

Three Camels

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Three young men travelled across the desert toward the tent of The Great Sage, seeking precious advice.

The eldest of the three moved in front of The Great Sage, who was meditating, and said, "God bless You, Great Sage! Our Father, before dying, left us these camels, and it is his will that I should have a half of the herd, my brother Ali one third, and my brother Ismail one ninth. We've tried, Glorious Sage, we have divided the camels and divided them again until the void opened before us. Help us, Magnificent Sage, we are not gifted with your superior intellect!"
camels riddle

The Great Sage asked the pleading man "How many camels are there?"

"Seventeen, may God bless You!", was the answer.

The Great Sage smiled.

How were the camels divided, strictly observing the fatherly will and without butchering any of them?

Three Camels Puzzle Solution

The Great Sage added his own camel to the other seventeen. He then gave 9 camels (one half of 18) to the eldest of the three, 6 camels (one third) to Ali, and 2 camels (one 9th) to Ismail. Then took his own camel back and sat in front of the tent, thanking God for His generosity.

Another way to explain the solution, perhaps in a more mathematical manner, is the following, courtesy of Gopalakrishnan Thirumurthy.
The three sons are assigned their shares: 1/2, 1/3, and 1/9. The sum of their shares is 1/2 + 1/3 + 1/9 = 17/18. Out of 18 camels, 17 of them are left by their father. So,
  • #1 gets 1/2 of 18 = 9
  • #2 gets 1/3 of 18 = 6
  • #3 gets 1/9 of 18 = 2
9 + 6 + 2 = 17.

Friday, October 10, 2014

Faulty Batch

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A little nation in Antarctica has its gold coins manufactured by eight different European companies. The Treasury Minister and his secretary were examining samples just delivered from the eight companies.

"How much should these coins weigh?" the Minister asked.

"Ten grams each, Sir."

"At least one of these coins - this one - is lighter than the others," said the Minister. "Let's check."

He put the coin on the scale, which showed that the coin weighed only nine grams. A bunch of coins, untidily placed on a tray, were frantically searched by the Minister and his secretary. Within the bunch, they found a handful of coins that also weighed one gram less than they should. The two men looked at each other; obviously, one of the manufacturing companies was producing coins with the wrong weight.

"Most of the coins are still packed in the plastic wrappers. It should be easy to tell which company is producing the faulty batch," said the secretary.

The two men placed eight packs of coins on the table, one pack from each company.

"How tedious," sighed the Minister. "Do we really have to use this scale eight more times, just to find the faulty batch of coins?"

"That won't be necessary, Sir," grinned the secretary. "We can find the lighter coins by using the scale only once."

How would they do it?

By using the scale once, it means that only one reading can be taken after all the coins to be weighed are placed onto the scale. ie, you cannot read the values as you place the coins on -- that would make the puzzle too easy!

Faulty Batch Puzzle Solution

The secretary placed on the scale 1 coin from the first batch, 2 from the second, and so on until he put 8 from the eighth batch.

If all coins weighed 10 grams each, then the weight displayed on the scale should have been 360 grams ((1 + 2 + ... + 8) × 10). But, since one batch of coins weighs less, the difference between 360 grams and the weight displayed on the scale should point us to the faulty batch. For example, if the faulty batch was the fifth one, then the total weight displayed on the scale would be 355 grams. Or if it was the seventh batch, the weight would have been 353 grams, ie 7 grams less than the theoretical total weight of 360 grams.

An 'optimisation' on this solution is to omit the 8 coins from the eighth batch. In this case, the maximum weight of the coins would be 280 grams, and if it equals 280, then the eighth batch is the faulty one. Thanks to Denis Borris for this observation.

By using the same logic, one could omit the coins from any one of the other batches, instead of the eighth one. For example, if we omit the fourth batch, we'll be left with a theoretical 320 grams and, if it is indeed the total weight, then we will know that the fourth batch was the faulty one. Thanks to Glen Parnell for noticing this.

Saturday, September 20, 2014

Red Square, Moscow, 30th April

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"And what about these two posters?"

"Those are the posters that will be hung on the south side of Red Square: as you can see they represent comrades Lenin and Marx."

"I can see that by myself. What I meant was the other two posters over there, the one with the Red Star and the one with the Hammer and Sickle."

The four posters were lined up and showed, from left to right, Lenin, Marx, the Red Star, and the Hammer And Sickle.

"Oh, they are nothing but the back of the other two. I wanted you to also see the back-faces of the posters, as these back-faces will be invisible from the inside of the Square."

communist posters riddle

"Hmmm... so enlighten me, which is the front of the poster representing the Hammer And Sickle?"
Nikita Proskoijev grinned, "I would like to test your deduction capabilities, dear comrade; a capability, I might add, which some people have had the guts to doubt. I say that all posters representing Lenin show the Hammer And Sickle on their opposite face. How would you verify this statement, in such a way that leaves no shadow of a doubt?"

"Do you mean, dear tovarisc, that I should turn these gigantic posters around to see which comrade matches the Star and which the Hammer And Sickle?"

"I have said what I have said, dear Ivanovic; it is up to you to decide what is the minimum number of posters to turn around to verify whether my statement was true or false."

Ivanovic felt very cold, as if he was in Siberia. What is the minimum number of posters, out of the four displayed, that he has to turn around to verify the statement of that cunning snake?

Ivanovic had to turn around two posters: the first one (Lenin) and the third one (the Red Star).

All that Nikita Proskoijev said was that all the posters representing Lenin show Hammer And Sickle on their opposite face. Therefore it is needed to check the back of the first poster and the front of the third one, to make sure that the Red Star wasn't linked with Lenin's face, cause if it was, then Proskoijev's statement would have been false.

Checking the front of the fourth poster (which is what Ivanovic did, that's why he's now a lumberjack near Jakutsk) is useless; if the 4th poster shows Lenin face as its front, it would just confirm what Proskoijev stated; but then, if the 4th poster showed Marx, this would not have falsified Proskoijev's statement, because he said that Lenin is linked to Hammer And Sickle, while he didn't state that Hammer And Sickle are linked to Lenin.

Friday, September 5, 2014

Amazing Life-Sized Games

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A lot of creative experiments take place every day around the world. IN this gallery we want to present you several board games, computer games or brain teasers made life-sized. These games were created for entertainment, as well as to assist people achieve e better orientation in space. Enjoy the gallery!

1. A group of anonymous artists known as ‘Bored‘ has created a life-size version of Monopoly using the streets of Chicago as their giant game board.

2. In honor of the board game's 60th anniversary in 2009, the crookedest street in the U.S., Lombard Street, San Francisco, was transformed into the sweetest board game around - Candyland.

3. On the 3rd annual Michigan Fallapalooza in 2007 - a day of games, music and sidewalk sales, the life-sized game of Hasbro's popular Chutes and Ladders was perhaps the most attractive event.

4. The world's biggest game of Scrabble was played out on the pitch at Wembley stadium.

5. The world's biggest Chess set by Guinness has a the King that is coming in at 48 inches high.

6. Human-sized Angry Birds was made in the Mount Faber in Singapore and it is super fun!