Ancient Mayans used a base-20 numbering system involving the number zero
Mathematics
Long before most world civilizations, the Maya developed a sophisticated vigesimal number system that utilized a shell symbol to represent zero as a functional placeholder.
The Maya civilization utilized a base-20 system instead of the base-10 method common today, likely because they counted using both fingers and toes. They represented numbers using only three symbols: dots for ones, bars for fives, and shells for zero.