Matchstick Mathematics

Dec 28, 2009

RAY: Go out and get yourself 16 matchsticks. You're going to use the matchsticks to make the following Roman numeral sequence. One, then two matchsticks to make a plus sign. Plus Roman numeral two. Plus Roman numeral three. Plus Roman numeral four, which is not "IV," but, in this case, "IIII." It would look like this: I + II + III + IIII.

TOM: If you add this up, one plus two plus three plus four, it adds up to 10.

RAY: Right. The question is, can you move one matchstick, without removing it, still using them all -- and make that equal to four?
RAY: Here's the answer. Take the plus sign between the one and the two, take the vertical matchstick, and put it horizontally in front of the one, so now the equation reads minus one, minus two, plus three plus four equals what?

TOM: Four!

RAY: And a lot of people have trouble with this because the idea of putting a negative sign in front. Anyway, do we have a winner?

TOM: You bet we have a winner. The winner is Sue Goodney from Bloomington, Indiana, and for having her answer selected at random from among all the correct answers that we got, Sue is going to get a $25 gift certificate to the Shameless Commerce Division at the Car Talk section of And with that gift certificate, she can get a copy of our music CD, "Car Talk, Car Tunes," which includes my brother's anthem, "They're all Jerks."

RAY: Congratulations Sue!

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