What building has the most stories?

You may enter, but you may not come in. I have space, but no room. I have keys, but open no lock. What am I?

What numbers should go on the bottom line?
3 6 9 15
8 2 10 12
11 8 19 27
19 10 29 39
? ? ? ?

Can you divide the below-given shape into four equal and identical pieces?

The first box has two white balls. The second box has two black balls. The third box has a white and a black ball.

Boxes are labeled but all labels are wrong!

You are allowed to open one box, pick one ball at random, see its colour and put it back into the box, without seeing the colour of the other ball.

How many such operations are necessary to correctly label the boxes?

John went to a parrot shop in Mexico, and the parrot owner told him that his parrot is so unique that he repeats everything he hears. John got excited and immediately bought the parrot. John went home and spoke many words, but the parrot does not repeat anything.
He went again to the parrot shop and complaint to the shopkeeper, but the shopkeeper never lied. Explain?

If two's company, and three's a crowd, then whats four and five ?

Replace the question mark with the number below given a simple math problem.

I have an eye but still cannot see.

Who am I?

What number comes next in the series?

5 15 5 18 5 24 14 20 _