Look at the picture and find out which square is not linked with any of the other squares.

A word I know,
Six letters contain,
Subtract just one,
And twelve is what remains.

Find the missing letter in the last circle logically in the given below picture.

I am white when I am dirty, and black when I am clean. What am I?

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

Replace the question mark with the number below given a simple math problem.

Two natural numbers have a sum of less than 100 and are greater than one.

John knows the product of the numbers and Jacob knows the sum of numbers.

The following conversation takes place between them:
John: 'I am not aware of those numbers.'
Jacob: 'I knew you wouldn't be. I am not aware myself.'
John: 'Now I know them!'
Jacob: 'Now I know them, too!'

What are the two numbers?

When Jack was six years old he hammered a nail into his favourite tree to mark his height. Ten years later at age sixteen, Jack returned to see how much higher the nail was. If the tree grew by five centimetres each year, how much higher would the nail be?

In the picture, you can see a chess board. On the top left position, the K marks a knight. Now, can you move the knight in a manner that after 63 moves, the knight has been placed at all the squares exactly once excluding the starting square?

What does it mean?