Non-decimal currency

A non-decimal currency is a currency which has sub-units that are a non-decimal fraction of the main unit, i.e. the number of sub-units in a main unit is not a power of 10.

Contemporary non-decimal currencies

Today only two countries in the world use non-decimal currencies. These are Mauritania (1 ouguiya = 5 khoums) and Madagascar (1 ariary = 5 iraimbilanja). However these are only theoretically non-decimal, as in both cases the value of the main unit is so low that the sub-unit is too small to be of any practical use and coins of the sub-unit are no longer used.

The official currency of the Sovereign Military Order of Malta, which retains its claims of sovereignty under international law and has been granted permanent observer status at the United Nations, is the scudo. The scudo is subdivided into 12 tari (singular taro), each of 20 grani with 6 piccioli to the grano. It is pegged to the euro (at a rate of 1:0.24).

All other contemporary currencies are either decimal or have no sub-units at all.

Historic non-decimal currencies

Historically, the use of decimal sub-units was the exception rather than the rule. Decimalised currencies show an advantage in accounting, because amounts are written down and calculated using the decimal numeral system (but when another numeral system is used, such as the vigesimal system that was common among ancient Mesoamerican civilizations or the sexagesimal system used by the ancient Mesopotamians, this advantage disappears). However,...
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