Non-decimal currency Non-decimal currency A non-decimal currency is a currency that 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. Today only two countries in the world use non-decimal currencies. Both of these countries are in Africa. 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
Decimal Day '2p' in the UK and simply '2' in Ireland. Decimal Day On 15 February 1971, known as Decimal Day, the United Kingdom and Ireland decimalised their currencies. Under the old currency of pounds, shillings and pence, the pound was made up of 240 pence (denoted by the letter "d" for Latin "denarius" and now referred to as "old pence"), with 12 pence in a shilling and 20 shillings (denoted by "s" for Latin "solidus") in a pound. The loss of value of the currency meant that the "old" penny, with the same diameter as the US half-dollar, had become of