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?

All of Jacob's shoes are red except two.
All of Jacob's shoes are green except two.
All of Jacob's shoes are yellow except two.

How many shoes does Jacob have?

What does the following represent?

N N N N N N N

A A A A A A A

C C C C C C C

How high do you have to count before you use the letter “a” in the English spelling of the whole number?

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

If 1+9+8=1, what is 2+8+9?

Can you count the number of triangles in the given figure?

What four weights can be used to balance from 1 to 30 pounds?

There was a competition where the contestants had to hold something. At the end of the event, the winner was a person who had no hands or feet. What was it that the contestants had to hold?

Using four sevens (7) and a one (1) create the number 100. Except for the five numerals, you can use the usual mathematical operations (+, -, x, :), root and brackets ()