Henry Ernest Dudeney (1857 – 1930) was an English author and mathematician who specialized in logic puzzles and mathematical games. He is known as one of the country's foremost creators of mathematical puzzles.
First, print and cut the pieces below. Then, arrange them so that they form a triangle and then rearrange them so that they form a square.
The solution is shown below.
What is fascinating about these dissections is that one can transform into the other by keeping the pieces attached to each other in a chain and simply
A man leaves home and makes three left turns, only to return home facing two men wearing masks. Who are those two men?
The person is a baseball player. The men are a catcher and an umpire.
There are 5 houses and each of them has a different color. Their respective owners have different heritages, drink different types of beverages, smoke different brands of cigarettes, and look after different types of pets. It is known that:
The question is, who owns the pet fish?
The German owns the pet fish.
Since the Norwegian lives in the leftmost house (9) and the house next to him is blue (14), the second house must be blue. Since the green house is on the left of the white house (4), the person living in the center house drinks milk (8), and the green house’s owner drinks coffee (5), the fourth house must be green and the fifth one must be white. Since the Brit lives in the red house (1) and the Norwegian lives in the leftmost house (9), the leftmost house must be yellow and the center house must be red. Therefore, the colors of the houses are: YELLOW, BLUE, RED, GREEN, WHITE.
Since the Norwegian from the yellow house smokes Dunhill (7), the man from the blue house must keep a horse (11). The person smoking Blends cannot be in the red house, because this would imply that the person in the green house keeps cats and the Swede keeps dogs in the white house (2, 10). However, in this case the Dane must be drinking tea in the blue house (3) and the person smoking Blends does not have a neighbor drinking water (5), which is a contradiction (15). Also, the person smoking Blends cannot be in the green house, because this would imply that the person in the white house drinks water (15), the Dane lives in the blue house (3), and the German and the Swede live in the last two houses. Since the German smokes Prince (13) and the Swede keeps dogs (2), there is nobody who could smoke Bluemaster and drink beer (12). The person smoking Blends cannot be in the white house either, because this would imply that the person in the green house drinks water (15), when in fact he drinks coffee (5).
Therefore, the person smoking Blends must be in the blue house, and then the German and the Swede must live in the last two houses (2, 13). Since the person who smokes Bluemasters drinks beer (12), this must be the Swede with his dogs in the white house (2). The only option for the person who smokes Pall Mall and raising birds (6) is the red house. Then the Norwegian must keep cats (10) and the German is left with the pet fish in the green house.
Can you recognize which famous movies are depicted by these images?
A woman was standing in her hotel room, when somebody knocked on the door. When she opened the door, there was a man who said that he has mistaken his door, apologized, and continued down the corridor. When the woman closed the door, she called security to warn them about the thief. Why did she think the man was planning to rob her?
If the man really thought this was his room, he wouldn’t have knocked on the door.
Alex and Bob are playing a game. They are taking turns drawing arrows over the segments of an infinite grid. Alex wins if he manages to create a closed loop, Bob wins if Alex does not win within the first 1000 moves. Who has a winning strategy if:
a) Alex starts first (easy)
b) Bob starts first (hard)
Remark: The loop can include arrows drawn both by Alex and Bob.
In both cases, Bob wins. An easy strategy for part a) is the following:
Every time Alex draws an arrow, Bob draws an arrow in such a way that the two arrows form an L-shaped piece and either point towards or away from each other. Since every closed loop must contain a bottom left corner, Alex cannot win.
For part b), Bob should use a modification of his strategy in part a). First, he draws a horizontal arrow. Then, he splits the remaining edges into pairs, as shown in the image below. If Alex draws one arrow on the grid, then Bob draws its paired arrow, such that the two arrows point either towards or away from each other. The only places where a loop can have a bottom left corner are where Bob drew the first arrow or the grid points directly above it. However, if a loop has a bottom left corner there, then it is easy to see that it must have at least one more bottom left corner elsewhere, which is impossible.
Two twins are lying next to a king and a queen in a large room. Yet, there are no adults and there are no children in the room. How is it possible?
The twins, the king, and the queen, are all (types of) beds.
White to move and mate in 6. Can you tell what is so unusual about this puzzle?
What is so unusual about this puzzle is that there is only one possible income of the game. The moves are as follows:
On this Dutch poster from WW2 you can see four pigs. Print the poster and try to find the fifth pig.
After folding the poster along the lines, you will get the portrait of the fifth pig, Adolf Hitler.
“Can you Spot It?” is a short vision/focus test made by Lenstore. You will be shown five images and you will have 45 seconds to find the hidden object in each of them. Press the START button to begin the test. Good luck!
The solutions are shown below.
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