What do you think with the below Picture ?

Why Aeroplane windows are round?

Can you solve this amazing hard number series problem?
7, 8, 10, 12, 16, 18 ?

A brand new Mobile Phone was on sale at 20% as a promotional offer. By what per cent must the Mobile price be increased to sell it at the original price again?

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

A pond had 60 fish, out of which, all but 20 died.
How many fishes are now present in that pond?

There was a man he lives in a hotel each morning he presses the first floor button each evening if there is a person in the elevator he asks him to press the 10 floor button if there is no one in the elevator he takes the stairs why.

I am never scared but became petrified and can’t live in a house but would die to make one. What am I?

A mules travels the same distance daily.
I noticed that two of his legs travels 10km and the remaining two travels 12km.
Obviously two mules legs cannot be a 2km ahead of the other 2.

The mules is perfectly normal. So how come this be true ?

Complete the table series riddle by finding the number that can replace "??".