What is the next number in this series?

4,12,84,3612....

I have no doors but I have keys, I have no rooms but I have space, you can enter but you can’t leave! What am I?

A mother is 21 years older than her child. In exactly 6 years from now, the mother will be exactly 5 times as old as the child.
Where's the father?

I was speeding and ran through a stop sign, yet two traffic officers who were there do nothing about it.

why?

I have a clock(12-hour format) and both the needles of the clock overlap at 12:00.
After how much time, they will overlap again?

Two trains start at the same time, one from Bangalore to Mysore and the other from Mysore to Bangalore. if they arrive at their destinations one hour and four hours respectively after passing one another, how much faster is one train running than the other?

I add 5 to 9 and get 2. The answer is correct, so what am I?

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

A mathematician couple was having a Frappuccino in Starbucks sitting opposite to each other. Suddenly the guy noticed the text written on the paper in front of them and exclaimed that it was wrong. The girl denied it and said it is appropriate. Both are correct. What is written on the paper?

Can you find a number that lies one third of the distance between 1/3 and 2/3?