Stumpers: The Reference Librarian’s Worst Nightmare

Carnac the Magnificent
“Carnac the Magnificent” via Wikipedia

When I was a child I was my father’s accomplice in crime. (That’s a lie.)  When I was young, I was my father’s assistant in a magic act.  (That’s an overstatement.  Here’s the truth.)  Years ago, I was my father’s foil in a math trick he perpetrated on the neighborhood children. In this trick he made the kids select a three digit number (say 723), inverse it (327), then subtract it from the original.  The trick is that the remainder would be a three digit number whose middle number is nine, and the first and third numbers when added together always equal nine.  (Try it!) Why am I telling you this?  You’ll see. Continue reading