How Many Letters
How many letters does the correct answer to this puzzle contain?
SOLUTION
Four – the only number which has the same number of letters as the number itself.
Category: Brain Teasers
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Seven Bridges
This is a map of old-time Kongsberg. The green shapes are bridges which connect the different parts of the city. Can you find a path through the city which goes through every bridge exactly once?
SOLUTION
No, you cannot. Notice that, except for the first city and the last city section you finish, the number of bridges used in every other section is even. However, there are three sections with an odd number of bridges, and therefore you cannot use all bridges exactly once.
Funky Mate
Place only 2 rooks and 1 knight on the board, so that the Black player is mated.
SOLUTION
You can place the rooks on c5 and e5, and the knight on f5.
Apples or Strawberries
What is heavier – 1 pound of apples or 1 pound of strawberries?
SOLUTION
They are equally heavy – 1 pound each.
Missing Pawns
White to play and mate in 4 moves.
Remark: The position on the diagram is one which occurs in actual play.
SOLUTION
Notice that the black queen and the black king have switched positions. However, this can happen only if some pawns have been moved. Therefore, we can conclude that the bottom row on the diagram is actually the 8th row of the chessboard. All black and all white pieces have reached their respective opposite sides of the board.
Now, White’s first move is Kb8-d7. The only moves black can play are with the knights. If Black plays Kb1-a3, Kb1-c3 or Kg1-h3, white mates in 2 more moves – Kd7-c5 and Kc5-d3. If Black moves Kg1-f3, then after Kd7-c5 Black can delay the mate by playing Kf3-e5. However, after the white queen takes it with Qxe5, Kc5-d3 is unavoidable.
Marathon
You are running a marathon and right at the finish line, you pass the runner in the 2nd position. In which place do you finish the marathon?
SOLUTION
You finish 2nd. Before passing the runner you were at 3rd place.
Snail on a Tree
A snail is trying to climb a
SOLUTION
Seven days only. After the sixth day, the snail would have climbed 6 meters. During the seventh day, it will climb 4 more meters and will get to the top.
Burn the Ropes
You have two ropes and a lighter. Each of the ropes burns out in exactly 60 minutes, but not at a uniform rate – it is possible for example that half of a rope burns out in 40 minutes and the other half in just 20. How can you measure exactly 45 minutes using the ropes and the lighter?
SOLUTION
First, you light up both ends of the first rope and one of the ends of the second rope. Exactly 30 minutes later the first rope will burn out completely and then you have to light up the other end of the second rope. It will take 15 more minutes for the second rope also to burn out completely, for a total of 30 + 15 = 45 minutes.
Running Dog
Two people – Mick and Goof, 100 meters apart, start walking towards each other with constant speeds of 2m/s. At the same time Mick’s dog starts running back and fourth between them with constant speed of 6m/s until Mick and Goof meet. How much distance does the dog cover in total?
SOLUTION
Mick and Goof will meet after 100/(2 + 2) = 25 seconds. Therefore the dog will run for 25 seconds and will cover 6 x 25 = 150 meters in total.
Missionaries, Cannibals
Three missionaries and three cannibals must cross a river with a boat which can carry at most two people at a time. However, if on one of the two banks of the river the missionaries get outnumbered by the cannibals, they will get eaten. How can all 6 men cross the river without anybody gets eaten?
Remark: The boat cannot cross the river with no people on board.
SOLUTION
Label the missionaries M1, M2, M3 and the cannibals C1, C2, C3. Then:
1. M1 and C1 cross the river, M1 comes back.
2. C2 and C3 cross the river, C2 comes back.
3. M1 and M2 cross the river, M1 and C1 come back.
4. M1 and M3 cross the river, C3 comes back.
5. C1 and C2 cross the river, C1 comes back.
6. C1 and C3 cross the river.
Now, everyone is on the other side.