The official currency of the Federation of Phantom Islands is the Phantom Islands Lithra (FPL). The currency was introduced on March 1, 1920, one day after the Federation was founded. It was meant to provide a common currency between the islands, which beforehand had used colonial currencies (such as the British pound, Spanish dollar, or French franc) or native systems of trading.
The currency's most common denominations are the 1, 2, 5, 10, 20, 50, 100, 200, and 500 lithra banknotes, and the 2, 1, 1/2, 1/4, 1/5, 1/10, 1/20, 1/50, and 1/100 lithra coins. However, several non-decimal denominations are in circulation, and many bespoke coins and notes have been released for certain occasions. For example, on March 14, 2015, a π lithra note was announced for Pi Day. The Phantom Islands lithra's mints are headquartered on Rica de Plata and Rica de Oro because of tyheir abundance of silver and gold respectively.
To encourage use of the currency, the Central Bank of the Federation of Phantom Islands (CBoFoPI) uniquely compounds interest continuously — thus giving it the nickname of "Euler's Bank". The lithra also receives redesigns every decade, with each denomination representing an important part of Federation of Phantom Islands history. Official currency exchanges are available in all major cities that provide hassle-free conversion of any world currency to lithras.