Look at this sequence from top to bottom. What is the next number in the sequence?
1
11
21
1211
111221
312211

Can you find a five letter word that is left with only two letters if one is removed?

What is the fewest number of coins that would be required in order to make sure each and every coin touches exactly three other coins?

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

Imagine you are in a room with no windows or doors. How will you get out?

Here is what you have to do. You have to throw a ball as hard as you can but it must return back to you even if it does not bounce at anything. Also, you have nothing attached to the ball. There is no one on the other end to catch that ball and throw it back at you.

How will you do it?

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

John speaks the truth only once a day in a week. Below are a few hints for you:

First: Days are Sunday, Monday and so on.
Second: One day he says, "I lie on Monday and Tuesday".
Third: On the next day, he says, "Today is either Thursday, Saturday or Sunday".
Fourth: On the next day, he says, "I lie on Wednesday and Friday".

Can you identify the day on which he speaks the truth?

Jack was having a candle light dinner with his girlfriend. Suddenly a cold gush of wind entered through the open window and three of the ten candles were extinguished. Assuming that none of the other candles were extinguished.

How many candles are they left with in the end ?

I went to the bookshop and spent one-half of the money that was in my purse.

When I came out, I found that I had as many cents as I had dollars and half as many dollars as I had cents when I went in. Find the money in my purse when I entered the store.