50 Ouguiya

Mauritania's ouguiya is one of only two world currencies not based on a decimal system — one ouguiya divides into five khoums, a structure rooted in Islamic traditions of fractional calculation rather than colonial metric standardization. The bimetallic format adopted for this denomination in 2004 reflected a broader regional trend among West African central banks toward higher-durability coinage as paper notes in lower values were withdrawn from circulation.