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?

By including only four matchsticks in below picture, you have to make "Four Triangles And Two Squares"

Queen Elizabeth organised a royal party.

To Avoid uninvited guest royal family set a password.
Jack (an uninvited person) plan to enter the party. He stand nearby the door.

First guest comes, the security person said 'twelve' and guest replied with six.
Second guest comes , the security person said 'six' and guest replied with 'three'.

Jack thought is enough and he walked to the entry point. The security person said 'eight' , Jack replied smilingly 'four'.
He was immediately thrown out of the party. why ?

What will be the best approach to finding all the prime numbers less than 75 that leave an odd reminder when we divide them with 5?

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

Look at the below sequence of letters and tell us what the next letter should be:

O T T F F S S ?

Why did the Girl throw the butter out of the window?

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

What does this mean?

CCCCCCC

Find out the missing number in the picture attached: