One of the coins of the Roman monetary system. The denarius (meaning "containing ten") was a silver coin worth at first ten, then, by the time of the Third Servile War, sixteen, of the bronze as coins which were the original Roman currency. As Roman trade with the Greek cities to the east and south increased through the mid-third century B.C., the Romans found themselves in need of a counterpart to the silver Greek drachma, and the Romans began striking the coin which became known as the denarius. By the time of the Third Servile War, the denarius was the primary coin of the Roman Republic, with a purchasing power, measured in terms of staples such as bread and wine of approximately £12 or $20 in 2010 currency.
The denarius was worth four sesterces throughout the Republic. While the denarius circulated far more widely, the sesterce was the more common unit of accounting. At the time of the Third Servile War, a private legionary was paid approximately 40 denarii three times a year (minus deductions for food and other expenses), although the stated salary was 450 sesterces per year.