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

Solve the following series:
AZ, GT, MN, __, YB

Using mathematical symbols like +, -, and x in order to make the equations correct. Replace # with the above-given symbols.

9 # 8 # 7 # 6 # 5 # 4 = 91

Which is heavier: a ton of bricks or a ton of feathers?

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

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

A man dies of old age on his 25 birthday. How is this possible?

You want to boil a two-minute egg. If you only have a three-minute timer (hourglass), a four-minute timer and a five-minute timer, how can you boil the egg for only two minutes?

A man says, "Brothers and sisters, have I none, but that man's father is my father's son." Who is that man?

A shepherd had 18 sheep, out of which, all but ten died.

Can you tell us how many sheep was he left with?