Babylonian mathematics were written using a sexagesimal (base-60) numeral system. The Babylonian system of mathematics was sexagesimal, or a base 60 numeral system. The Babylonian system of mathematics was a sexagesimal (base 60) numeral system. Sumerian has a combination decimal and sexagesimal system (for example, 600 is 'ten sixties'). He employed a sexagesimal system that was derived from Babylonian mathematics. Mesopotamian mathematics and science was based on a sexagesimal (base 60) numeral system. The fractional parts of chord lengths were expressed in sexagesimal (base 60) numerals. Zero was indicated by a space between sexagesimal numerals. With so many factors, many fractions involving sexagesimal numbers are simplified. This sexagesimal system became the standard number system in Sumer and Babylonia. The Greeks limited their use of sexagesimal numbers to the fractional part of a number. One sixtieth of this, using their standard sexagesimal divisions, was a degree. Binary clocks that display time in binary-coded sexagesimal also exist. A numbering system based on sixty was used, a sexagesimal system. The Greek sexagesimal placeholder or zero symbol changed over time.