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      Scientific American February 1981

      Mathematical Games, February 1981

      Gauss's congruence theory was mod as early as 1801

      • By Martin Gardner on February 1, 1981

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      More in the February 1981 issue of Scientific American
      • Advances in Antisubmarine Warfare
      • The Nok Sculptures of Nigeria
      • Autoimmune Diseases
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