From Poof to Proof: Inside the Mind of a Mathemagician
For mathematician and "mathemagician" Arthur Benjamin, the best way to illustrate the basic concept of algebra is with a little magic trick: "Think of a number between one and ten. Now, double it. Add ten. Then, divide by two. Subtract the number you started with originally.”
Then, he explains why the trick works: "Let's call the number you started with n—and right away, we've achieved the major goal of algebra, which is the concept of abstraction, using a letter to represent a value that we don't know. First, you doubled the number, so you had 2n. Then, you added 10, so you had 2n + 10. After that, you divided the number by 2. When you divide 2n + 10, you get n + 5. Finally, when you subtract n—no matter what number it is—you're left with 5."
That's just one example of how Benjamin, who is well known for his magic shows in which he performs mental calculations at lightning speeds, demonstrates the fun and fascinating aspects of math in his latest book, The Magic of Math: Solving for x and Figuring Out Why.
