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?

How many times do a clock's hands overlap in a day ?

You are in a room that has three switches and a closed door. The switches control three light bulbs on the other side of the door. Once you open the door, you may never touch the switches again. How can you definitively tell which switch is connected to each of the light bulbs?

A sundial has the fewest moving parts of any timepiece. Which has the most?

If I put in one bird per cage, I have one bird too many. If I put in two bird per cage, I have one cage too many. How many cages and birds do I have?

If eleven plus two equals one, what does nine plus five equal?

Three playing cards in a row. Can you name them with these clues? There is a two to the right of a king. A diamond will be found to the left of a spade. An ace is to the left of a heart. A heart is to the left of a spade. Now, identify all three cards.

Place the numbers from 1 to 9 in the circles in a manner that each side of the triangle sums up to 17.

I have branches, but no fruit, trunk or leaves. What am I?

Can you divide the below-given shape into four equal and identical pieces?