Which number should replace the question mark?

John is asked to stand behind Jacob and Jacob is asked to stand behind John. Both of them feel confused about it and don't know what to do?

But it is quite possible, do you know how?

I throw two dice simultaneously.

What is the probability of getting a sum as 9 of the two numbers shown?

Which city is three-fifths chick two third cat and 50% goat?

I am the fastest animal but cannot climb the tree. What am I?

What has six faces, but does not wear makeup, has twenty-one eyes, but cannot see? What is it?

Count the squares in the matchstick puzzle below?

Can you count the number of blocks in the picture below?

Find the hidden panda in the image below.

John and his wife were living in a rural place. On a particular day, John's wife fell ill and he called the local doctor. When the doctor picked up, he said, "Doctor, my wife is ill. She might have appendicitis."

"This can't be possible! I took out her appendix two years ago myself," the doctor explained.

When diagnosed, John's wife was found to have appendicitis. How can this be possible?