Replace the question mark with the correct number in below Picture:

A certain street contains 100 buildings. They are numbered from 1 to 100. How many 9's are used in these numbers?

What number do you get when you multiply all of the numbers on a telephone's number pad?

A man has eighty-one cows ( numbered 1,2,3...81 as such). The beauty is that cow no. 1 gives 1ltr of milk, cow no. 2 gives 2ltrs of milk and so on. The man wants to equally distribute the cows among his nine sons so that each one of them gets the same quantity of milk.

How many times can you subtract the number two from the number fifty?

Okay before we begin with the puzzle, do keep in mind that you have to answer it quickly.

You are participating in a car race. Seeking the perfect moment, you overtake the second person in the race. What positions are you in now?

10+10 and 11+11 can give you the same answer.

Explain how?

Which is the smallest number that you can write using all the vowels exactly once?

In the attached figure, you can see a chessboard and two rooks placed on the chess board. What you have to find is the number of squares that do not contain the rooks. How many are there?

I have cities, but no houses. I have mountains, but no trees. I have water, but no fish. What am I?