Matchstick Math Number 3E

Jun 07, 2014

RAY: Get a bunch of matches and make the following equation with Roman numerals: XI, that's 11, plus I, then an equals sign and X. So you have XI plus I...

TOM: Eleven plus one.

RAY: Eleven plus one equals ten.

TOM: That's not right.

RAY: That's not right and the question very simply is: What is the fewest number of matches you can move to get an equation that is correct? You can't throw away any matches -- you have to use them all.

I’ll give you a hint. I presented this to my son the other day, my younger son, and he looked at it for a minute. We had it set up on the kitchen table. He leaves the room, and as soon as he re-enters, he has the answer.

RAY: 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. As he stood there at my side and looked at the equation, he said, "Gee, I don't know, Dad. I can certainly move a match and make the thing correct," 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 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: The winner is Jim Shaughnessy from Troy, New York. Congratulations!

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