What is the coolest letter in the alphabet?

No one wants to have it, but if one got it, he does not want to lose it. What is It?

A 3 digit number is such that it's unit digit is equal to the product of the other two digits which are prime. Also, the difference between it's reverse and itself is 396.

What is the sum of the three digits?

You need to climb ten stairs. At every stair, you can either take one step up or you can jump two steps up.

In how many different ways you can climb 10 stairs?

Can you find the missing letter in the sequence?
S - T - I - L - ? - T - F - Y - C

Can it be possible to build a house that has all its four walls facing towards the South?

I have Rs.50 and I spend it in the way as below.

I’m orange, I wear a green hat and I sound like a parrot. What am I?

The below given figure comprises of a pattern through which you can determine the missing letter. Can you push your mind to find the pattern and add the missing letter?

The first box has two white balls. The second box has two black balls. The third box has a white and a black ball.

Boxes are labeled but all labels are wrong!

You are allowed to open one box, pick one ball at random, see its colour and put it back into the box, without seeing the colour of the other ball.

How many such operations are necessary to correctly label the boxes?