Which number should replace the question mark?

A donkey is behind another donkey
I'm behind that second donkey
But there is a whole nation behind me

It is a murder you can describe in a word.

When you stop to look, you can always see me. But if you try to touch me, you can never feel me. Although you walk towards me, I remain the same distance from you. What am I?

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

I make a loud sound when I’m changing. When I do change, I get bigger but weigh less. What am I?

Two in a corner, one in a room, zero in a house, but one in a shelter. What am I?

You need to move three matchsticks to form three squares. Can you do it?

From a pack of 52 cards, I placed 4 cards on the table.

I will give you 4 clues about the cards:

Clue 1: Card on left cannot be greater than the card on the right.
Clue 2: Difference between the 1st card and 3rd card is 8.
Clue 3: There is no card of an ace.
Clue 4: There are no face cards (queen, king, jacks).
Clue 5: Difference between the 2nd card and 4th card is 7.

Identify four cards?

Why do you find that most of the buildings are deprived of the 13th floor?

I am a normal creature, but I have five hands. I can even have more but even then I will be considered normal.

Who am I?