What is the coolest letter in the alphabet?

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

Do you know of a place where the wind blows south and then suddenly shifts direction towards the north?

Find the number of squares in the below-given picture.

In the given picture, you can find two letters missing. When two particular letters are placed in the missing spots, you get an eight-letter word while reading in the anti-clockwise direction. Can you find out the missing letters and the missing word eventually?

What has six faces, but does not wear makeup, has twenty-one eyes, but cannot see? What is it?

Which word does the below Plexor means ?

Three people enter a room and have a green or blue hat placed on their heads. They cannot see their own hat but can see the other hats.
The colour of each hat is purely random. They could all be green, blue, or any combination of green and blue.
They need to guess their own hat colour by writing it on a piece of paper, or they can write 'pass'.
They cannot communicate with each other in any way once the game starts. But they can have a strategy meeting before the game.
If at least one of them guesses correctly they win $10,000 each, but if anyone guesses incorrectly they all get nothing.
What is the best strategy?

Can you name four days which start with the letter 'T'?

I am not a bull but I have horns.
I am not an ass but I have a pack saddle.
Wherever I go, I leave silver behind me.

Who am I?