RAY: You're back with us, Click and Clack, the Tappet Brothers, and we're hear to talk about cars, car repair and the answer to last week's Puzzler. Now, this is another in the very famous "matchstick" series.
TOM: I think this one was the best.
RAY: Ah, you do, hunh?
TOM: Yeah.
RAY: Anyway, in order to participate in this Puzzler, you had to have had either a bunch of matchsticks or toothpicks, or pen and paper to draw the matchsticks. And here it is. You get your matchsticks and you make the following equation with Roman numerals: XI, which is 11.
TOM: Let me write this. X1.
RAY: Plus I.
TOM: Plus I, which is one.
RAY: One. Equals X. OK. So, it's XI plus one equals X, which is clearly wrong. It says 11 plus one equals, what? Ten.
TOM: Not everyone knew it was wrong.
RAY: Those who knew it was wrong...
TOM: The people who took new math.
RAY: Well.
TOM: This is old math.
RAY: As Tom Lederer says, "The goal is not to get the right answer, but to understand what you're doing."
TOM: Right.
RAY: So, the question was, very simply: What's the fewest number of matches you can move to make the equation correct? And I said that the plus sign and equals sign matches are fair game, but you can't throw away any matches. Of course, I obfuscated. As you'll soon find out.
TOM: But the basic question was, how...what is the least number of matches you can? Is that the question?
RAY: Yes, the smallest number of matches.
TOM: Yeah, yeah.
RAY: OK. And the hint that I gave is that when I presented this to my younger son, Andrew, the other day, he got the answer after he had left the room and returned.
TOM: That's brilliant. I thought that was brilliant.
RAY: A brilliant, brilliant hint.
TOM: A brilliant hint. That's what I'm saying. I thought that was a brilliant hint--after I knew the answer, of course.
RAY: As he stood there at my side and looked at the equation, he said, "Gee, I don't know, Dad." He said, "I can certainly move a match and make the thing correct," he said. And I told him, "Well, you don't have to move any matches." Wow. And he walked out of the room bewildered, and when he came back...
TOM: Was he just bewildered or was he going, "Stupid jerk." He mumbled.
RAY: But when he came back he had the answer, because if you walk around to the other side of the table and look at the equation...
TOM: You see it upside down.
RAY: You see it as X equals I plus IX.
TOM: Man.
RAY: And you have to move no matches to make the equation correct. Who's our winner this week, Tommy?
TOM: Wow. How would I know, I've been so spellbound here I haven't even looked. Here it is. The winner is Jim Shaughnessy from Troy, New York. And for having his correct answer chosen from among the thousands of correct answers that we had this week, Jim is going to get a copy...
[ Car Talk Puzzler ]
