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

O T T F F S S ?

A King wants to send the diamond ring to his girlfriend securely. He got multiple locks and their corresponding keys. His girlfriend does not have any keys to these locks and if he sends the key without a lock, the key can be copied in the way. How can King send the ring to his girlfriend securely?

What is the largest amount of money that you can possess in change and still if someone asks you for a dollar, you won't be able to give?

John and Jacob are twin brothers. One of them is a liar whereas the other one is a truth-teller.

I called their home number and one of them picked up.
I asked. 'Does John lie?' The person replied with a yes.

Whom did I talk with, John or Jacob?

A dying old man wants to divide his entire land between his only two sons. Since his only wish is to treat them as equal as both of them have been too good to him, he wants to divide his land equally between them. The problem is that the land is significantly irregular in shape and thus there is no choice of cutting them into two equal halves.

Can you help him divide the land in a manner that both of his sons will be happy?

Which word is least like the others? Third, fourth, fifth, sixth, seventh, eighth, ninth?

How many times in a given day, minutes and hour clock comes in a straight line ?

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

What is the next number in the series?

15 29 56 108 208 ?

I had an infinite supply of water and 5 litres and 3 litres jars.

How would you measure exactly 4 litres in the least number of steps?