There are 2 cops parked along a one-way street looking for traffic violations. They spot a taxi driver going in the wrong direction, yet they do nothing.

Why?

Until it is measured, not known. Yet how you miss it when it has gone. What is it?

There were two grandmothers and their two granddaughters.
There were two husbands and their two wives.
There were two fathers and their two daughters.
There were two mothers and their two sons.
There were two maidens and their two mothers.
There were two sisters and their two brothers.
Yet there are only six, who are buried here,
All are born legitimate and relationships clear.
How can this happen?

Can you count the number of triangles in the given figure?

Identify the hidden meaning behind this picture?

A certain street contains 100 buildings. They are numbered from 1 to 100. How many 9's are used in these numbers?

Why do Chinese men eat more rice than Japanese men do ?

Can you arrange four 9's and use at most 2 math symbols, to make the total 100?

You are in a room with no metal objects except for two iron rods. Only one of them is a magnet.
How can you identify which one is a magnet?

I am the black child of a white father, a wingless bird, flying even to the clouds of heaven. I give birth to tears of mourning in pupils that meet me, even though there is no cause for grief, and at once on my birth, I am dissolved into air. What am I?