Look at the below sequence of letters and tell us what the next letter should be:

O T T F F S S ?

Two guards were on duty outside a barracks. One faced up the road to watch for anyone approaching from the North. The other looked down the road to see if anyone approached from the South. Suddenly one of them said to the other, "Why are you smiling?"

How did he know his companion was smiling?

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

You need to climb ten stairs. At every stair, you can either take one step up or you can jump two steps up.

In how many different ways you can climb 10 stairs?

Can you figure out the logic I used to decide the order of the following words:
gun, shoe, spree, door, hive, kicks, heaven, gate, line, den

Can you find out the missing number?

? 4 5 3 5

9 5 7 10 3

I have Rs.50 and I spend it in the way as below.

Three doctors said that Bill was their brother. Bill says he has no brothers. How many brothers does Bill actually have?

There are three boxes on a table. One of the box contains Gold and the other two are empty. A printed message contains in each box. One of the message is true and the other two are lies.

The first box says "The Gold is not here".

The Second box says "The Gold is not here".

The Third box says "The Gold is in the Second box".

Which box has the Gold?

Find the next number in the sequence

5 12 24 36 ?