# Why is a circle divided into 360 Degrees ?

**Stop and think for a moment , we live in a world where our main number system is in base 10 so why do we have the rather odd base 60 for time and angles. Why not decimal time or decimal segments to represent angles in a circle ?**

Even in the twenty-first century, time and angles continue to be reckoned in the same weird units used by the Sumerians over 4,000 years ago. Quite how it started is still debated by historians but one theory, first put forward 200 years ago, links it to the calendrical “circle” of a year.

Sumerian mathematicians spotted that the number of days in a year is close to 360, an integer whose prodigious number of factors makes it easy to chop up into smaller parts. The awkward five days left over were declared public holidays. Another theory argues that it comes from the base-60 arithmetic used by the Sumerians. A circle can easily be divided up into six equal parts by marking off points along its circumference at spacings equal to its radius. If each of these parts is taken to be 60 units, then a full circle will be 360 units – which we now call degrees.