There are 20 people in an empty, square room. Each person has full sight of the entire room and everyone in it without turning his head or body, or moving in any way (other than the eyes). Where can you place an apple so that all but one person can see it?

There is a box full of marbles,
all but two are blue,
all but two are green,
and all but two are red.

How many marbles are in the box?

Today, I celebrated my 32nd birthday but I was born in 1972.
How is this possible?

When you say goodbye, I am what you need to tie.
I come as a couple and go wherever you run.
Who am I?

These types of puzzles are known as charades. What you have to do is find two words that are referred to in the first stanza and the second stanza and put them together to form the third word in the third stanza.

Just for example, if my first refers to 'off' and my second refers to 'ice', then my whole will be office.

My first is present - future's past -
A time in which your lot is cast.

My second is my first of space
Defining people's present place.

My whole describes a lack of site -
A place without length, breadth, or height.

Take away my first letter, then take away my second letter. Then take away the rest of my letters, yet I remain the same. What am I?

How can you leave a room with two legs and return with six legs?

You are mixing a mixture of cement and Sand with five gallons of water. You have a garden hose giving you all the water you need. The problem is that you only have a four-gallon bucket and a seven-gallon bucket and neither has graduation marks. Find a method to measure five gallons.

Nine marbles are arranged in the image below. Can you slide two marbles to form a square?

When can we add 2 to 11 and get 1 as the correct answer?