What is the fastest way to double your money?

How far can you walk into the woods?

How many times can you subtract the number 5 from 25?

Find the next number in the series

12, 20, 40, 72, 116, 172 ?

People put me on the table and cut me but do not eat me. What am I?

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

A chess tournament is taking place on knock-out terms (the one who loses the match is out of the game).
(a) If 10 matches are played in total, how many players participated?
(b) If 20 players took part in the tournament, how many matches were played?

10+10 and 11+11 can give you the same answer.

Explain how?

The doctor advised his patient to take a tablet after every fifteen minutes. He gave him five tablets in total.

How much time will he take to have all the five tablets?

What occurs twice in a week, once in a year but never in a day?