I developed this "mathmatical" formula for my history classes for some global perspective. It is a powerful lesson for my students. In fhis post-9/11/01 world, many of our students usually associate Islam with terrorism. I use this simple lesson as a way to show that any religion or ideology, when taken to extremes and used for the wrong purpose, can become a very bad thing. This has a tremendous impact on many of my students as they can use empathy to see the point.