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Mathematics (HMC)

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I still recall my thrill and disappointment when I read Mathematical Carnival, by Martin Gardner. I was thrilled because, as my high school teacher had recommended, mathematics was presented in a playful way that I had never seen before. I was disappointed because it contained a formula that I thought I had "invented" a few years earlier. I have always had a passion for mental calculation, and the following formula appears in Gardner's chapter on "Lightning Calculators." It was used by the mathematician A. C. Aitken to mentally square large numbers.


First published in the College Mathematics Journal, vol. 43, no. 1 (January 2012), pg. 58-63, by the Mathematical Association of America.

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© 2012 Mathematical Association of America

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