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?

You have two strings whose only known property is that when you light one end of either string it takes exactly one hour to burn. The rate at which the strings will burn is completely random and each string is different.

How do you measure 45 minutes?

What has 13 hearts but no other organs?

How much will a 38° angle measure when looked at under a microscope that magnifies ten times?

What 4-letter word can be written forward, backward or upside down, and can still be read from left to right?

If you’ve got me, you want to share me; if you share me, you haven’t kept me. What am I?

If 5 cats catch 5 mice in 5 minutes, how long will it take one cat to catch a mouse?

What is in seasons, seconds, centuries and minutes but not in decades, years or days?

I noticed one of the words in the oxford dictionary is spelled incorrectly. What about you?

If,

20 % 5 = 24

21 % 7 = 33

42 % 6 = 67

Then;

66 % 6 = ?