Here’s a complicated word for a simple skill: It combines the Greek prefix “dactylo,” meaning “finger,” with the suffix “-onomy,” meaning “a system of knowledge.” In short, dactylonomy is counting on your fingers. However, it’s a bit more complicated than counting to 10 on one’s fingers (or 20 with the toes). In fact, various systems of dactylonomy have been recorded around the world dating back as far as first-century Persia. These versions offered the ability to count into the thousands and even greater numbers using the fingers and other parts of the hand. It’s commonly believed that the decimal system was popularized because of the universal experience of counting to 10 on one’s fingers.