What Adam and Eve do not have but the rest of the people have?

Find The Next Number in this series.
1, 2, 6, 42, 1806 ?

Client Dempsey living in one of the East Coast states of the U.S. was talking to Landon Donovan, who was living in the West Coast state of the U.S.

Dempsey: What time is it?
Donovan: Wow, It is the same time here.

How is this possible?

Which letter of the alphabet has the most water?

Most people think of me as money. But when they find me in the water, they won’t get any money out of me. What am I?

A number can be multiplied by multiple of nine
i.e 9 18 27 36 45 ...

and the resulting number consist of only one digit.

Can you identify the number ?

Considering the below equation:

V + II - VI = 10
IV - X + VIII = 20
IV - VII + VI = 30

Then, I + II + III = ?

Replace the question mark with the correct number below.

It comprises roots which nobody sees,
Much taller than those trees,
Up and up it goes,
Still it never grows?

You stand in front of two doors. A guard stands next to each door. You know the following things: one path leads to paradise, the other leads to death. You cannot distinguish between the two doors. You also know that one of the two guards always tells the truth and the other always lies. You have permission to ask one guard one question to discover which door leads to paradise. What one question would you ask to guarantee you enter the door to paradise?