Why do people go to bed?

Replace the question mark with the correct number.

While house hunting in London, I came across a very good leasehold property Discussing the lease the landlady told me:

'The property was originally on a 99 years lease and two-thirds of the time passed is equal to four-fifths of the time to come. Now work it out for yourself and see how many years are to go!

I am a white box having no key or lid.
Yet there is a golden treasure inside it.

What Am I?

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?

John named his first son Alpha, second Beta, third Charlie and fourth Delta. What is the fifth son's name?

Prove that twice of ten is the same as twice of eleven.

How many runs at maximum can a batsman score in a normal one-day match? Consider the fact that the conditions are ideal and there are no No Balls, no Wide Balls and no Extras in that match.

A boy was locked in a room by some robbers. All that is in the room is a piano, a calendar, and a bed. The room is locked from the outside. What does he eat, drink, and how does he escape and get out?

What has hands, but can’t clap?