The square root of number 121 is "11". What is the square root of the number "12345678987654321."?

Name a key which is hardest to turn.

There is one thing that goes round the house and also inside the house but never even share a brief touch. What is it?

Mr Red Lives in the red house.
Mr Green Lives in the greenhouse.
Mr Yellow Lives in the yellow house.

Who lives in the Whitehouse?

The captain of a ship is telling you an interesting story and then poses a question. He says, “I have travelled the oceans far and wide. One time, two of my sailors were standing on opposite sides of the ship. One was looking west and the other one east. And at the same time, they could see each other clearly. Can you tell me how that was possible?”

I am a word that begins with the letter “i.” If you add the letter “a” to me, I become a new word with a different meaning, but that sounds exactly the same. What word am I?

For an extra income, John decided to work at a Hotel for one hour daily. The manager offers him that they will pay him $11 after every 11 days.
However, John offered a different proposition to the manager. The offers stand as:
He will be paid just a penny on his first day.
Two pence will be paid on the second day,
Four pence will be paid on the third day.
And so on till the 11th day.

Should the Hotel manager accept his offer?

You can take four of the five letters out of this word, but the pronunciation never changes. What is the word?

Find the next number in the sequence

5 12 24 36 ?

I noticed one of the words in the oxford dictionary is spelled incorrectly. What about you?