What goes up but never comes down?

Can you solve the maths in the below-given picture equation?

I have teeth but i don't bite. Who Am I ?

Below the four parts have been reorganised. The four partitions are exactly the same in both arrangements. Why is there a hole?

A boy and his father are caught in a traffic accident, and the father dies. Immediately the boy is rushed to a hospital, suffering from injuries. But the attending surgeon at the hospital, upon seeing the boy, says 'I cannot operate. This boy is my son.' How is this situation explained?

Make the seating arrangement of 10 children in such a way that there are 5 rows with 4 children in each row.

John and his team plan to rob a safe. They got just one chance to break the code else the local police will be informed. Below are clues:
A) Exactly one number is perfectly placed: 9 8 1
B) Everything is incorrect: 9 2 4
C) Two numbers are part of the code of the safe but are wrongly placed: 0 9 3
D) One number is part of the code of the safe but is wrongly placed: 1 4 7
E) One number is part of the code of the safe but is wrongly placed: 7 8 3

Look at the picture and find out which square is not linked with any of the other squares.

The day after tomorrow will be three days before Tuesday. Can you find out what is today?

I have a five and a three-gallon jar. Assuming there is an infinite supply of water, how can I measure one-gallon water?