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

I am 5 letters long.
My first two tell you who I am
My first 3 could be a medicine
My last three reversed could be a young boy.
My 4th, 3rd and 2nd in that order could be a fruit drink.
If you have me you may hang me round your neck
WHAT AM I ?

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

Can you find a pattern and the missing number in the series given below?

100, 155, 258,? , 584, 819.

Find the last number in the series below:

voN luJ yaM raM ---

Can you find the mistake in the below statement?

I know a ten-letter word in the English language which can be typed using only the top rows of the computer keyboard.

Below toothpicks/matchsticks indicate the group of fishes moving from west to east direction. Can you make them move from east to west by just moving three toothpicks/matchsticks?

What is the four-digit number in which the first digit is one-third the second, the third is the sum of the first two, and the last is three times the second?

The more you take me, the more you leave me behind.
Who Am I?