As the Romans expanded their republic and subsequent empire, they did so with the fighting skills and technical savvy of their legions; but it has been argued that trade was the under-girding impetus and support behind this expansion.
Towards the development of trade, then, a comprehensive and precise accounting system was used in Roman trade. A Roman abacus, which used Roman numerals, worked well in tallying Roman measures and in counting Roman money. Counting boards were also utilized.
As with other things Roman, their units of measurement borrowed extensively from the Greeks, although Mesopotamian, Egyptian, and Hebrew influences can be seen, as well.
One chalcus (called “chalcus” in Latin) was equivalent to 1/48th of a Drachm. This coin weighed about 71 milligrams.
One siliqua (“siliqua”) was equivalent to 1/18th of a Drachm, and weighed about 189 1/3 milligrams.
One obolus (“obolus”) was equivalent to 1/6th of a Drachm, and weighed about 0.568 grams.
One scruple (“scrupulum”) was worth 1/3 of a Drachm, and weighed about 1.136 grams.
One dram (“drachma”) weighed about 3.408 grams.
One shekel (“sicilicus”) was worth 2 Drachms, and weighed about 6.816 grams.
One ounce (“uncia”) was worth 8 Drachms, and weighed about 27.264 grams.
One pound (“libra”) was worth 96 Drachms, and weighed about 327.168 grams.
One mine (“mina”) was worth 128 Drachms, and weighed about 436.224 grams.
A “sescuncia” was the term the Romans used to call one and a half ounces.
Coins used through the majority of the Roman Republic and into the western half of the Roman Empire included the aureus, a gold coin; the denarius, a silver coin; the sestertius, a bronze coin; the dupondius, a bronze coin; and the as, which was a copper coin. These coins were in use for a span of some six hundred years.
Eventually, the denarius was replaced by the coin then called the double denarius, but now is usually referred to as the radiate or antoninianus. This coin was later replaced, in turn, by the creation of such denominations as the argenteus, a silver coin, and the follis, which was a silvered bronze coin. After this monetary reform by Diocletian, Roman coins mainly included the solidus, a gold coin, and small bronze coins in varying denominations.
Unlike the majority of modern coinage, Roman coins carried an intrinsic value; although they contained precious metals, they weren’t bullion. At the beginning of the Roman Empire, the value of a denarius was worth a day’s pay for a Roman Legionnaire.