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?

How far can you walk into the woods?

What can go through glass without breaking it?

A frog is at the bottom of a 30-meter well. Each day he summons enough energy for one 3-meter leap up the well. Exhausted, he then hangs there for the rest of the day. At night, while he is asleep, he slips 2 meters backwards. How many days does it take him to escape from the well?

When I got four, I have it none.
When I got two, I have it some.
When I got none, I have it all.

What is it?

The product of three consecutive numbers is 7980.
Then the sum of these consecutive numbers would be?

What is the fastest way to double your money?

The person who makes it has no need for it. He who purchases it does not use it. The person who does use it does not know they are. What is it?

A wooden log balances equally on the scales when weighed with three-quarters of a pound and three-quarters of a wooden log.

Can you calculate the weight of the entire wooden log?

Count the number of squares in the picture below.