I had a very interesting experience recently with a number puzzle that I would like to share with others. At a mathematics convention, I saw a friend, Evelyn Graham of Chesapeake, Virginia, who thrust nine little cardboard squares, each containing one of the digits, I through 9, into my hand and challenged me to … well, due to convention noise and the fact that when Mrs. Graham is enthusiastic and excited about something, she tends to talk faster than I can listen, I came away with two ideas. First, the digits had to be arranged in the shape of a triangle, and second, it had to be magic (meaning that each row should add up to the same number).