Hy people! I have just received this image from my brother via gmail. We had very similar mathematical optical illusion at the very start of this website, and I find this kind of illusions hardest to solve. Maybe this should belong to some new category called “Brain Teasers” or “Mighty Puzzles“, still we can probably pull this one of as part of the illusion site as well. So, the question follows: if all the shapes that form these two rectangles below, are of the same shape and areas, how come the overall surface of the second is bigger? Where is the mistake? How do you explain this one?