The Babylonians develop a base–60 (sexagesimal) place–value numeration system (as opposed to our base–10 system), where the value of a digit depends on its relative placement in the sequence.
With 12 factors (1, 2, 3, 4, 5, 6, 10, 12, 15, 20, 30 and 60) in their system, the Babylonians had rich mathematical material to play with.
The Babylonians inherited key components of the base–60 system from earlier Sumerian civilization. The Babylonian system is, of course, the basis of our 60–minute hour system.