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

I have nine bottles of wine and one of the nine bottles is poisoned.
I need to find the poisoned bottle with two facts
(1) Poison is deadly, only a sip will cost death
(2) I have two mice to do so.

How should I do it?

Solve the rebus riddle in the picture below.

You see a mathematical expression in the picture. Can you think of a movie that this expression refers to?

I cannot talk, but I always reply when spoken to. What am I?

f you were running a race, and you passed the person in 2nd place, what place would you be in now?

Replace the question mark with the correct number.

A detective visits his friend John just to discover that John's neighbour Dr Jacob was murdered. Dr Jacob, who is a mathematician wrote the murderer's name in a code word "Hcqtfz". There were five suspects
1. Ajit
2. Pankaj
3. Ganpat
4. Deenu
5. Hariya

The Detective was instantly able to find the murderer.
Can you?

If we add four times the age of John four years from now to five times his age five years from now we get ten times his current age.

How old will John be two years from now?

Can you think of any three-dimensional shape that comprises of exactly two surfaces?