• Journal for History of Mathematics
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• v.33 no.6
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• pp.315-325
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• 2020

In this study, how Choi Seok-Jeong made Hadoguodo is presumed. Choi SeokJeong's Hadoguodo does not actually reflect the Hado. But it is verified that Hadoguodo reflecting Hado can be made. In addition, it is verified that Hadoguodo can be made so that not only the sum of the nine numbers of each square are all 207 but also the sum of the nine numbers in the horizontal and vertical directions are all 207.