Logic Books

Human was never a strongest, or quickest among the animals. It had never had a sharpest claws or longest teeth. Still, it became the dominant specie in the world. How? Because of his brain and ability to solve the most complicated problems! 

I was one of the best in school and University in logic, participated in many team games trying to solve the most complicated puzzles, and in most times my team was on top. 

Somehow many puzzles helped me in real life! (No shit! The puzzle with treasure sharing is one of the best puzzles to understand interest, negotiation and problem solving! I used it A LOT when I was a lawyer). 

So I wrote a book with the most interesting puzzles I had on me life. Even if you can't solve them, please, read the solution, and that can give you an inspiration and bring you to the next level of thinking!

So far I am planning to make two more logic books! So, stay tuned!

The 200 Even Mind Boggler Puzzles

Second book with the collection of the best puzzles I've encountered in my life!

Honestly, I think it is even better than the first one. 

It has the same chapter as the previous one, with one additional chapter, where you are to solve the consequences of Susha's attempt to solve some problems. I found it rather funny. 

The Ultimate 200 Mind Boggling Puzzles

The best puzzles I met in my life. The book I can definitely recomend to buy. 

Keep in mind it has new cover now!

This is the old cover of the book

If you already have it, please wait for another book to be released!

Top 10 puzzles from the book

The Answer

One of them (for example, Pi) should divide treasure into three piles that are equal to him and he would gladly accept either of them. Then Susha and Harrrharrrov pick the pile that looks the largest. Pi takes the remaining one. If Susha and Harrrharov picked the same pile, Pi can take any of the remaining two. Now there are just two participants left. If they choose different piles - they take them and everybody is happy. If they picked the same pile, the treasure should be mixed and devided the same way, but with two participants and two piles.

2. Far in the Ancient East, a dying man bequeathed 19 camels to his three sons. According to the will, the eldest son was to get half of the camels, the middle son - a quarter, and the youngest - a fifth. But the brothers began to argue because 19 camels are not divisible, neither by 3, nor by 4, nor by 5. They went to the sage, who also had camels. And the wise man was able to judge them, and everyone received the number of camels according to the will.

How did he do that?

The Answer

The sage added 1 camel to the brothers’ herd. Then he gave 10 camels to the elder brother, who was to receive one half of the herd. Then he gave 5 camels to the brother who was to receive one quarter. And finally, he gave 4 camels to the youngest brother, who was to receive one-fifth of the herd. Then, he took his camel back.

3. Ancient Spartans highly valued conciseness and brevity. Once a lame warrior came to the King to be hired in the phalanx. King refused him. Then the warrior said this phrase, and was immediately accepted.

What was the phrase?

The Answer

“I thought you needed those who can fight, not who can run away.”

4. Young Pi had an exam in the language of sushi. He knew it very bad, but he knew a doctor Doevenless. Pi came to the exam and honestly passed it.

How did Pi manage to do this?

The Answer

Pi asked the doctor Doevenless to set a plaster cast on his wing. Then he memorized the story of how he allegedly broke it in Sushian. Of course, the examiner asked him how he broke the wing, and Pi told the learned story to the examiner.

5. Name a crop that is 90% burned and 10% wasted.

The Answer

A tabacco.

6. Several firms were competing with each other. They were selling their products via specially printed catalogs. Stores didn’t care much and were placing them randomly in stacks, one on another. A director of one of them hired Pi so he could increase his sales. And Pi did this to the catalog. First, the director was furious, but then he got Pi was right.

What did Pi do?

The Answer

Pi decreased the format of the catalog. It became smaller, which made the director furious. But as it became the smallest catalog, stores had to put it on top of the stacks so it wouldn’t collapse.

7. Pi decided to play the stock market. He bought 10 shares in Susha Fish very Ltd for 100 pebbles. But things didn’t work out for Susha - all the fish was sold and eaten and Susha hadn’t caught a new yet. And the shares of Susha Fish very Ltd on a penguins’ stock market dropped to 50 pebbles per share. Harrrharov came to Pi and said that Susha had gone fishing and soon the shares would grow up. Not up to 100, but up to 75 pebbles for sure!

Question: What does Pi need to do to make a profit?

The Answer

Though Pi expected Susha Fish very Ltd shares to grow, and they dropped, Pi should buy more of these shares. He had bought 10 shares for 100 pebbles. Now they cost 50 pebbles per share. This means, that if he buys 10 shares, their average cost would be 75 pebbles per share. If Harrrharov was right, Pi should buy more than 10 shares, further reducing the average cost of shares Pi had bought, increasing his profit, even the shares’ value dropped instead of rising, as he had expected.

8. One internet provider hired contractors to lay 49 power cables across the river. Every cable had the same color and no numbers. As soon as the provider saw that, he immediately fired them. He also hired Pi so Pi could mark every cable. He paid Pi for 49 trips across the river. But Pi, after some thinking, managed to mark every cable just in two trips.

Question: How did he managed to do that?

The Answer

First, Pi connected power to a random wire and marked it as #1. He attached all the remaining 48 wires in pairs to each other so that on this side of the river there were one powered wire and 24 pairs of other wires. How he does this is not important, the order of the pairs does not matter now too. After that, Pi went to the other bank of the river (the first trip).

When at the place, he found the powered wire with the tester - this was wire #1, as we remember. And then the electric magic began.

Pi took powered wire #1 and connected it to any other wire, then signed that wire as #2. As we remember, all wires were connected in pairs on the first bank of the river. This means, that wire #2 on that side was also connected to some other wire, and this means that the current will come back and appear in a new wire, which Pi would sign as #3.

Then everything went the same way: he took the wire under the current #3, connected it to any remaining wire, and signed the new wire as #4. He also remembered about the pairs on the other side, so he looked for the wire in which the current appeared again and signed it as #5. In the same way, he connected the remaining wires and numbered all the wires on the second side from 1 to 49. Having done this, Pi returned to the first bank (second trip).

The most interesting thing remains: how to put down the same numbers on the wires on this shore. Pi knew what wire #1 looked like because it was he who signed it, but he didn’t know how cable #2 looked.

But he remembered that wire #1 is connected on the other bank of the river to wire #2, which on this bank is connected to wire #3. So Pi’s task was to find this connection at the first bank, where he was. To do this, he disconnected all pairs in turn and checked if the current disappeared in all other wires. If it didn’t disappear in all the other wires, it means that he had disconnected the wrong pair, and connected them back. And if it disappeared, it means that Pi found the connection of wires #2 and #3. At the same time, the unknown wire that remained powered would be wire #2, and the one with which it had been connected will be #3.

After that, Pi connected the signed pair back, and started looking for the next wire, which would turn off all the other wires - these would be wires #4 and #5. Using this scheme, the cunning (and lazy) penguin Pi signed all the remaining wires. The provider needed just to disconnect wires’ pairs on the other bank.

9. You have 20 jars of tablets. Tablets are weighing 1 g in 19 of them, and in one jar tablets weigh 1.1 g. You can put it on the scales for the exact weight.

Question: How to find a jar of heavy pills just in one weighing?

The Answer

We only have one weighing. This means that we have to weigh many tablets at the same time. In fact, we have to weigh 19 cans at the same time. If we miss two (or more) jars, we won’t be able to check them. Don’t forget: only one weigh-in!

How to weigh several cans and understand which one contains the heavier tablets? Let’s imagine that we have only two jars. One of them contains heavier pills. If we take one tablet from each jar, and weigh them, their total weight will be 2.1 g, but at the same time we will not know which of the jars gave an additional 0.1 g. So, we need to weigh it somehow differently.

What will the scale show if we take one pill from jar #1, and two pills from jar #2? The result depends on the weight of the tablets. If jar No. 1 contains heavier tablets, then the total mass will be 3.1 g. If jar #2 contains heavier pills, then total mass would be 3.2 grams. So, this method we can use.

We can generalize our approach: take one pill from jar #1, two pills from jar #2, three pills from jar #3, and so on. Weigh this set of pills. If all the pills weigh 1g, then the result is 210g. The “surplus” will bring in a jar of heavy pills.

Thus, the jar number can be found by a simple formula:

(weight - 210)/0.1

If the total weight of the tablets is 211.3 g, then the heavy tablets were in jar No. 13 etc.

10. The friends could find only one ship that could bring them home. But it was a heavily loaded cargo ship, which could take only two passengers with no luggage of any kind.

The friends agreed that Susha and Harrharov would go with that ship, and Pi would send them treasure by post.

When Pi returned to the hotel owner laughed - the post was very famous for its stealing. They open every package they receive. There was no chance the treasures could reach Susha and Harrrharov by the post.

Pi though the sitiation over.

Pi has the lock and the key from it. Susha also has the lock and the key. The locks cannot be opened with some other key. So, if Pi would lock the treasure and sent it, Susha would not be able to open it with her key.

But if he would send the key, the post would surely open the treasure chest with it.

Question: How can Pi send the treasure if the only thing he can do is lock the treasure with his lock or open his lock?

The Answer

Pi should lock the treasure and send it to Susha. Susha would place her lock along with the Pi’s and then send it back to Pi. Then Pi removes his lock and sends it back to Susha. Susha opens her lock.

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