10 Ouguiya

Mauritania's ouguiya has been non-decimal since its introduction in 1973 — one ouguiya divides into five khoums, making it one of only a handful of currencies worldwide to use a base-5 subdivision. The nickel-plated steel composition adopted for this type replaced the earlier cupro-nickel, a cost-driven decision that became increasingly common across West African issues during the 2000s as raw material prices climbed.