where did the rule of 72 come from
Rule of 72 An early reference to the rule is in the Summa de arithmetica (Venice, 1494. Fol. 181, n. 44) of Luca Pacioli (1445â€“1514). He presents the rule in a discussion regarding the estimation of the doubling time of an investment, but does not derive or explain the rule, and it is thus assumed that the rule predates Pacioli by some time.
At sixes and sevens An ancient dispute between the Merchant Taylors and Skinners livery companies is the probable origin of the phrase.[1] The two trade associations, both founded in the same year (1327[2]), argued over sixth place in the order of precedence. In 1484, after more than a century and a half of bickering, the Lord Mayor of London Sir Robert Billesden ruled that at the feast of Corpus Christi, the companies would swap between sixth and seventh place and feast in each other's halls. Nowadays, they alternate in precedence on an annual basis.[1][2]