Each region set its interest rate for ease of calculation in the local system of fractions - Mesopotamia's sexagesimal (60-based) system, the Greek decimal system or the Roman duodecimal (12-based) system. To Heichelheim this seeming decline in the official Bronze Age rate from the 20 percent (1/60th per month) in the 3rd and 2nd millennia to 10 percent on Egypt and classical Greece, to 1/12th in Rome reflected the rising security of credit [...]