 Here's a basic algebraic exercise that illustrates the issue covered in the next segment. Let A equal 1 and B equal 1, then A equals B. We can multiply both sides of the equation by A. We can subtract B squared from both sides. We can factor A squared minus B squared into A plus B times A minus B on the left hand side of the equation. We can A B minus B squared into B times A minus B on the right side of the equation. We can divide both sides by A minus B and we can cancel out common terms in the fractions. So the equation simplifies to A plus B equals B. Substituting in the ones for A and B, we get 1 plus 1 or 2 equals 1. This happened because we divided both sides of the equation by A minus B, which equals 0. In this way, dividing by 0 is like a box of chocolates. You never know what you're going to get. A closer look at the number 0 will explain why.