What reflects like a mirror but can never be seen?

What has 4 fingers and a thumb, but is not living?

Which is correct, 9 and 5 is 13 or 9 plus 5 is 13?

What is drawn by everyone without a pen or pencil?

I fasten to walk, and unfasten to stop. What am I?

What invention lets you look right through a wall?

What’s the easiest way to double your money?

How many books can you put into an empty backpack?

What is the longest word in the English dictionary?

What always comes into a house through the keyhole?

Everyone has it and no one can lose it. What is it?

What two things can you never eat before breakfast?

When things go wrong, what can you always count on?

What can you share and still have all for yourself?

What has a head, a tail, is brown, and has no legs?