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 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?

Find out the missing number in the picture attached:

There was a strange boy who was born before his father. How can this be possible?

I am the black child of a white father, a wingless bird, flying even to the clouds of heaven. I give birth to tears of mourning in pupils that meet me, even though there is no cause for grief, and at once on my birth, I am dissolved into air. What am I?

How can you write nineteen in a manner that if we take out one, it becomes twenty?

If you remove one from eleven, it becomes ten. If you remove one from nine, it becomes ten.

How is this possible?

I am the one who remains awake when you sleep. But I need to rest when you awake. Who Am I?

You may enter, but you may not come in. I have space, but no room. I have keys, but open no lock. What am I?

There’s a one-story house in which everything is yellow. Yellow walls, yellow doors, yellow furniture. What colour are the stairs?