Arthur Benjamin is the Smallwood Family Professor of Mathematics at Harvey Mudd College, and is also a magician. His new book is The Magic of Math: Solving for x and Figuring Out Why.From his Q & A with Deborah Kalb:
Q: What do you think are some of the most interesting connections between math and magic?--Marshal Zeringue
A: Mathematicians and magicians both want their audience to wonder: How did you do that? The magician keeps the method secret, but the mathematician wants you to understand. Math is not just solving for X. It's also figuring out why.
Q: You write that 9 is the most magical number. Why is that?
A: As a kid, I loved the fact that the multiples of 9: 9, 18, 27, 36, and so on, had the magic property that their digits would always add to a multiple of 9.
Here's a magic trick based on this fact. Think of any two digit number. Add their digits together. (So if you were thinking of 42, the digit sum is 6.) Now subtract that sum from the original number. (Example: 42 – 6 = 36.) Now add your digits together. (Example: 3 + 6 = 9.) You should now be thinking of the number 9.
Q: What are some of your favorite strategies to encourage people who are scared of math or don’t like it?
A: I like to motivate math with...[read on]