From the Harvard Business Review:
The textbook in which these hand
signals appeared was written by Girolamo Tagliente in Venice in about
1515. According to one scholar, Tagliente’s book was printed throughout
the 16th century and did much to shape the teaching of math—a vital
discipline for merchants and tradesmen.
The marketplaces of Renaissance Europe were polyglot bazaars, attracting
traders from across the Continent and beyond, who spoke different
languages and carried different currencies. How did businessmen
communicate? And how did they stay abreast of exchange rates?...MORE