What number should come in place of the question mark below?

There are 2 people near the river and both of them want to get on the other side. The boat can only take one of them. But they got across.
How?

What demands an answer, but asks no questions

You can see it everyday, But cannot touch it at will. What is it?

Find the hidden tiger in the given optical illusion ?

Can you find out the number of the parking space in which the car is parked?

You can find some missing letters in the picture. By placing two particular letters in the spaces, you can form a nine lettered word beginning from one of the corners and going clockwise direction to the middle. Can you find out the letters and the word?

Can you count the number of triangles inside a triangle?

I am the one who remains awake when you sleep. But I need to rest when you awake. Who Am I?

How many bricks does it take to complete a building that is 15 feet wide, 30 feet deep, and 12 feet tall made of brick?