Before 2000 BC
Further information: Prehistoric numerals- c. 20,000 BC — Nile Valley, Ishango Bone: suggested as the earliest reference to prime numbers and Egyptian multiplication although this is disputed.
- c. 3400 BC — the Sumerians invent the first numeral system, and a system of weights and measures.
- c. 3100 BC — Egypt, earliest known decimal system allows indefinite counting by way of introducing new symbols, .
- c. 2800 BC — Indus Valley Civilization on the Indian subcontinent, earliest use of decimal ratios in a uniform system of ancient weights and measures, the smallest unit of measurement used is 1.704 millimetres and the smallest unit of mass used is 28 grams.
- c. 2000 BC — Mesopotamia, the Babylonians use a base-60 decimal system, and compute the first known approximate value of π at 3.125.
Read more about this topic: Timeline Of Numerals And Arithmetic