A Doctor always sneezes before the rain. Doctor sneezes, Will it rain?

Replace the question mark with the correct number below.

The person who makes it has no need for it. He who purchases it does not use it. The person who does use it does not know they are. What is it?

What is the next number in this series?

4,12,84,3612....

I am the beginning of everything, the end of everywhere. I'm the beginning of eternity, the end of time and space. What am I?

John was visiting his friend Jacob. He found out that his friend's wife had just killed a burglar in self-defense.
John asks Jacob about what happened and he told that "His wife was watching television when suddenly the bell rang. She thought that it is her husband Jacob but she found the burglar who attacked her instantly and she got so frightened that she killed the burglar immediately with the knife.
John asked the police to arrest his friend's wife. Why?

In the image given, you can find several triangles. Can you count them all?

One absent-minded ancient philosopher forgot to wind up his only clock in the house. He had no radio, TV, telephone, internet, or any other means for telling time. So he travelled on foot to his friend's place a few miles down the straight desert road. He stayed at his friend's house for the night and when he came back home, he knew how to set his clock. How did he know?

A man has to get a fox, a chicken, and a sack of corn across a river.

He has a rowboat, and it can only carry him and one other thing.
If the fox and the chicken are left together, the fox will eat the chicken.
If the chicken and the corn are left together, the chicken will eat the corn.

How does the man do it?

You bought me for dinner but never eat me. What am I?