Mathemagician!

Try these arithmetic tricks

- Ivars Peterson

When he was a kid, Arthur Benjamin liked to show off. Now he’s a math professor at Harvey Mudd College—and a professional magician.

Unlike some other magicians, Benjamin doesn’t pull rabbits out of hats. Instead, he amazes audiences by multiplying large numbers in his head super fast.

Benjamin says that anyone— young or old—can learn to do the same feats of mental arithmetic. All it takes is a memory for numbers and the trick of calculating from left to right.

Suppose you want to multiply 37 by 6. Starting from the left, you would multiply 30 by 6 to get 180. Then, 7 times 6 equals 42. Add 42 to 180 to get 222.