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

Three doctors said that Bill was their brother. Bill says he has no brothers. How many brothers does Bill actually have?

In the addition below, all digits have been replaced by letters. Equal letters represent equal digits and different letters represent different digits.
ABCABA
BBDCAA
ABEABB
ABDBAA
------- +
AAFGBDH
What does the complete addition look like in digits?

Consider this about a word: The first two letters signify a male, the first three letters signify a female, the first four letters signify a great, while the entire world signifies a great woman. What is the word?

The below mentioned letters have been placed in a order using a logic.

DEAD, BALL, FEAR, SHOP

Can you find the logic?

John is pretty weird. He likes toffees but hates chocolates. He loves books but never reads. He likes to build his troops in an online game but does not proceed with the war. He likes to go swimming but is afraid of water.

Seeking this behaviour, can you tell whether he likes balloons and parties?

What you cannot hold but it is yours?

Get total of 120 by using five zeros 0,0,0,0,0 and any one mathematical operator.
Do you ?

If you're 8 feet away from a door and with each move you advance half the distance to the door. How many moves will it take to reach the door?

At a party, there are five people and a whole round cake lying at the centre of the table. Only four people will make a cut and take their piece and the last one will get the remaining piece on the table. How can they make sure that everyone gets a 1/5th of the piece?