You will be required to perform a task. It is precisely to find the five differences between the two bills, and click on them with a mouse. Concentrate and note that distinctions can be either on the front side of the banknote, and at its back, the back side. Use the "gap" or scroll the mouse wheel to flip the bill. Collect as many points, and become a real currency expert. If you click past, you take away 200 points. Come on!