How many sides does a circle have?

A girl says this to her best friend: “I was born in 1955, and I celebrated my 17th birthday last weekend.” Her best friend thinks she’s lying, but she’s actually correct. How is that possible?

The more it dries, the wetter it becomes. Can you tell what it is?

How many times can you subtract the number two from the number fifty?

The more of this there is, the less you see. What is it?

You need to move three matchsticks to form three squares. Can you do it?

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

Jack was having a candle light dinner with his girlfriend. Suddenly a cold gush of wind entered through the open window and three of the ten candles were extinguished. Assuming that none of the other candles were extinguished.

How many candles are they left with in the end ?

Replace the question mark with the correct number in the below-given picture?

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?