Many have heard it, but nobody has ever seen it, and it will not speak back until spoken to. What is it?

Which part of London exists in France as well ?

If it took eight men ten hours to build a wall, how long would it take four men to build it?

You stand in front of two doors. A guard stands next to each door. You know the following things: one path leads to paradise, the other leads to death. You cannot distinguish between the two doors. You also know that one of the two guards always tells the truth and the other always lies. You have permission to ask one guard one question to discover which door leads to paradise. What one question would you ask to guarantee you enter the door to paradise?

Place the numbers from 1 to 9 in the circles in a manner that each side of the triangle sums up to 17.

Move three sticks of the spiral below to form a square.

The product of three consecutive numbers is 7980.
Then the sum of these consecutive numbers would be?

What can run but never walk, have a mouth that never speaks, have a head that never weeps, and have a bed but never sleeps?

Prove that twice of ten is the same as twice of eleven.

A bomb goes off.
Carnage.
One person, only a few feet away, survives! How can this be?