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

In the attached figure, you can see a chessboard and two rooks placed on the chess board. What you have to find is the number of squares that do not contain the rooks. How many are there?

If,

A + B = C
D - C = A
E - B = C

Based on the above equations, find out the answer for:

D + F = ?

Before reading ahead, you must know the fact that only one of the people here is telling the truth.

A says that B is lying.
B says that C is lying.
C says both A and B are lying.

Can you find out who is speaking the truth?

I have a head like a cat and feet like a cat, but I am not a cat. What am I?

Irene killed hundreds of people mercilessly and yet the police were not able to put her behind the bars. Why?

A finger goes in me. You fiddle with me when you're bored. The best man always has me first. What am I?

Railroad Crossing, look out for the cars. Can you spell that, without any R's ?

How do you go from 98 to 720 using just one letter?

Six glasses are in a row. The first three are filled with milk and the last three are empty. By moving only one glass, can you arrange them so that the full and the empty glasses alternate?