Replace the question mark with the correct number.

What is the next number in this series?

4,12,84,3612....

When you say goodbye, I am what you need to tie.
I come as a couple and go wherever you run.
Who am I?

Decode below three cipher riddles:

26 L of the A
7 D of the W
1000 Y in a M

I am a mother. However, I never give birth.

I am a father. However, I never nurse my children.

Wandering is not possible for me, but standing still happens occurs rarely.

Who am I?

If you're 8 feet away from a door and with each move you advance half the distance to the door. How many moves will it take to reach the door?

Which wheel of car does not rotate when you turn your car right?

What is in seasons, seconds, centuries and minutes but not in decades, years or days?

John was writing his first book. After saving the document, he locked his laptop with a password and mentioned some phrases for the hint box.

A friend of his tried opening his laptop but found out that it was password protected. Following is the hint that appeared.
1 mobile 3 books 2 roars 1 night 4 balls 2 lighters 1 ghost 1 hat 3 watches.

Can you help him in cracking the password?

For this puzzle, you might have to find logic in something illogical. But hey, it's fun and a healthy little break from your strenuous puzzle-solving sessions.

Can you decipher the meaning in the following cluster of letters?

ITIT,NCENTCENT