Why Aeroplane windows are round?

What is the next number in this series?

4,12,84,3612....

Replace the question mark with the correct number in the below-given picture?

What is the riddle which can be asked all day with a different correct answer each time.

In the given picture, you can find two letters missing. When two particular letters are placed in the missing spots, you get an eight-letter word while reading in the anti-clockwise direction. Can you find out the missing letters and the missing word eventually?

Can you find a rabbit in the given picture?

You walk into a room that contains a match, a kerosene lamp, a candle and a fireplace. What would you light first?

Living above a star, I do not burn
Eleven friends and they do not turn
I can just be visited in a sequence, not once or repeatedly
PQRS are my initials
Can you tell my name accurately?

Can you solve below mathematical equation?

2^1234 - 2^1233

What has no start, end, or centre?