Annual calendar years. An annual timepiece calendar is less complicated and expensive than a perpetual timepiece calendar, which will not require manual adjustment till 2100. That year will not be a leap year, even though its number is evenly divisible by 4. Ancient calendars (static) may always have been annual, even after the length of the calendar year was fixed at (avg.) 365.25 days by the Julian Calendar (46 BC). Early Romans observed an 8-day market week, called the nundinal cycle, until the seven-day week was adopted during the reign of Emperor Constantine the Great (306-337). A goal of modern calendar reform
Decimal calendar Decimal calendar A decimal calendar is a calendar which includes units of time based on the decimal system. The original Roman calendar consisted of ten months (however, the calendar year only lasted 304 days, with 61 days during winter not assigned to any month). The months of Ianuarius and Februarius were added to the calendar by Numa Pompilius in 700 BC. The ancient Egyptian calendar consisted of twelve months, each divided into three weeks of ten days, with five intercalary days. The French Republican Calendar was introduced (along with decimal time) in 1793, and was similar to the ancient Egyptian