81 x 9 = 801. What must you do to make the this equation true?

You are given a cube that is made with the help of 10x10x10 smaller cubes summing up to a total of 1000 smaller cubes. You are asked to take off one layer of the cubes.
How many remain now?

A train full of passengers goes through a tunnel. When the train comes out from the other end, there is no single person on the train.

How did it happen?

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

How many triangles are there in the picture below?

What number does the below three word/phrase identify and why?
1. Deck
2. Year
3. Singing in the Rain

Two trains start at the same time, one from Bangalore to Mysore and the other from Mysore to Bangalore. if they arrive at their destinations one hour and four hours respectively after passing one another, how much faster is one train running than the other?

There is a place where if I stand up straight, I will still be considered sideways.

How far can you walk into the woods?

A sea diver is a real show-off. He showed everyone that he can hold his breath underwater for 15 minutes.

I went to the diver and told him that I can be underwater for double the time i.e 30 minutes.
He responded that he will give me 100$ if I would be able to do it. I won 100$.

What did I do?