Why do you find that most of the buildings are deprived of the 13th floor?

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

O T T F F S S ?

Do you know who was buried in John's tomb?

A father is locked up in jail. His wife has gone bankrupt. Their male child has to sell his hotel in order to gain some money. Yet their girl child does not care and is quite happy.

How can someone be so rude?

There’s a girl who has a large family. She has an equal amount of brothers and sisters, but each brother only has half as many brothers and sisters. What’s the correct amount of brothers and sisters?

You are an expert on paranormal activity and have been hired to locate a spirit haunting an old resort hotel. Strong signs indicate that the spirit lies behind one of four doors. The inscriptions on each door read as follows:

Door A: It's behind B or C
Door B: Its behind A or D
Door C: It's in here
Door D: It's not in here

Your psychic powers have told you three of the inscriptions are false, and one is true. Behind which door will you find the spirit?

Solve this riddle by finding the odd one out from the rest.

What type of tree can I carry in my hand?

Find three whole, positive numbers that have the same answer when multiplied together as when added together.

Can you place three balls such that the equation shown in the picture holds true?