Best hard riddles

logicsimplecleanclever

Why are manhole covers round? Do manhole covers really need to be circular?
Manhole covers are round so that they won't fall through the hole into the sewer below them. No matter how you turn the cover, you won't be able to push the cover through the hole. However, if you were to have square manhole covers, you would be able to rotate the cover such that one of the edges of the square cover is lined up with the diagonal line of the square hole, which would allow the cover to fall through, causing countless problems that the general public would rather avoid.
73.93 %
55 votes
logicstorycleansimple

A wise man lived on a hill above a small town. The townspeople often approached him to solve their difficult problems and riddles. One day, two lads decided to fool him. They took a dove and set off up the hill. Standing before him, one of the lads said "Tell me, wise man, is the dove I hold behind my back dead or alive?" The man smiled and said "I cannot answer your question correctly". Even though the wise man knew the condition of the dove, why wouldn't he state whether it was dead or alive?
The man told the two lads, "If I say the dove is alive, you will the bird and show me that it is dead. If I say that it is dead, you will release the dove and it will fly away. So you see I cannot answer your question. Search: Schrödinger's cat
73.93 %
127 votes
logicsimpleclean

Two convicts are locked in a cell. There is an unbarred window high up in the cell. No matter if they stand on the bed or one on top of the other they can't reach the window to escape. They then decide to tunnel out. However, they give up with the tunnelling because it will take too long. Finally one of the convicts figures out how to escape from the cell. What is his plan?
His plan is to dig the tunnel and pile up the dirt to climb up to the window to escape.
73.90 %
78 votes
logicmath

Can you arrange four 9's and use of at most 2 math symbols, make the total be 100?
99 / .99 or 99 + 9/9
73.89 %
87 votes
trickywho am I

I am first in Earth, second in Heaven, I appear two times in a week. You can only see me once in a year, although I'm in the middle of sea. Who am I?
Answer is E The asnwer is E. As In spelling of Earth E comes first, in Heaven it comes second, in week it comes twice, in a year it comes once and finally in spelling of sea E stands in middle of the spelling.
73.86 %
1372 votes
clean

In which place are you silent?
In the building ("u" is silent in pronouncing "building".
73.80 %
50 votes
logicsimpleinterview

Mr. Black, Mr. Gray, and Mr. White are fighting in a truel. They each get a gun and take turns shooting at each other until only one person is left. Mr. Black, who hits his shot 1/3 of the time, gets to shoot first. Mr. Gray, who hits his shot 2/3 of the time, gets to shoot next, assuming he is still alive. Mr. White, who hits his shot all the time, shoots next, assuming he is also alive. The cycle repeats. All three competitors know one another's shooting odds. If you are Mr. Black, where should you shoot first for the highest chance of survival?
He should shoot at the ground. If Mr. Black shoots the ground, it is Mr. Gray's turn. Mr. Gray would rather shoot at Mr. White than Mr. Black, because he is better. If Mr. Gray kills Mr. White, it is just Mr. Black and Mr. Gray left, giving Mr. Black a fair chance of winning. If Mr. Gray does not kill Mr. White, it is Mr. White's turn. He would rather shoot at Mr. Gray and will definitely kill him. Even though it is now Mr. Black against Mr. White, Mr. Black has a better chance of winning than before.
73.75 %
91 votes