It is well known that Google has a stringent interview process. The search engine giant is known to ask questions of high standards that would leave many candidates scratching their heads.

Since the questions were extremely difficult, Google itself has now banned a few of them from being asked during interviews, The Independent reported. Some of these questions were listed by Seattle job coach Lewis Lin in 2009. Check them out below:

1) Explain a database in three sentences to your 8-year-old nephew.

2) You need to check that your friend Bob has your correct phone number, but you cannot ask him directly. You must write the question on a card and give it to Eve who will take the card to Bob and return the answer to you. What must you write on the card, besides the question, to ensure that Bob can encode the message so that Eve cannot read your phone number?

3) How much should you charge to wash all the windows in Seattle?

4) Why are manhole covers round?

5) How many piano tuners are there in the entire world?

6) A man pushed his car to a hotel and lost his fortune. What happened?

7) How many times a day does a clock's hands overlap?

8) How many vacuums are made per year in USA?

9) Explain the significance of "dead beef"

10) If a person dials a sequence of numbers on the telephone, what possible words/strings can be formed from the letters associated with those numbers?

11) You are shrunk to the height of a nickel and your mass is proportionally reduced so as to maintain your original density. You are then thrown into an empty glass blender. The blades will start moving in 60 seconds. What do you do?

12) How many golf balls can fit in a school bus?

13) You have to get from point A to point B. You don't know if you can get there. What would you do?

14) You are at a party with a friend and 10 people are present (including you and the friend). Your friend makes you a wager that for every person you find who has the same birthday as you, you get \$1 (£0.7,€0.89); for every person he finds who does not have the same birthday as you, he gets \$2. Would you accept the wager?

15) You have two eggs and get access to a 100-story building. Eggs can be very hard or very fragile, which means they may break if dropped from the first floor or may not even break if dropped from 100th floor. Both eggs are identical. You need to figure out the highest floor of a 100-story building an egg can be dropped without breaking. The question is how many drops you need to make. You are allowed to break two eggs in the process.

16) Every man in a village of 100 married couples has cheated on his wife. Every wife in the village instantly knows when a man other than her husband has cheated but does not know when her own husband has. The village has a law that does not allow for adultery. Any wife who can prove that her husband is unfaithful must kill him that very day. The women of the village would never disobey this law. One day, the queen of the village visits and announces that at least one husband has been unfaithful. What happens?