Base 60
Mesopotamian mathematics counts in sixties, and the clock still does.
- When
- Known to
- ± 300 years
- Era
- Bronze Age, Holocene
Sumerian and Babylonian mathematics uses a sexagesimal place-value system, probably because 60 divides evenly by 2, 3, 4, 5, 6, 10, 12, 15, 20 and 30, which makes fractions tractable without decimals. It gives us 60 seconds, 60 minutes, and 360 degrees in a circle. The system also included a positional notation — the same sign meaning a different value by position — which is a conceptual leap most later systems, including Roman numerals, failed to make.