Why did ancient cultures, such as the Mesopotamians, use sexagesimal (base-60)? I've been doing some reading on this, and there seems to be no consensus. Of course, it's rare that there's perfect consensus in archaeology and ancient history, but, as I see it, the answer is wildly different depending upon which author you consult.

Do we have any sense of why base-60 was chosen? It seems like such an oddly large base to choose (even if it was more of a 'fusion' of base-10 and base-60). Why not something smaller and 'countable'?

  • Human beings have five fingers on each of their four members, hence the use of decimal and vigesimal counting systems, such as that of the Maya, for instance. Apart from this, they also customarily divide things into halves, thirds, and quarters, hence the use of a dozenal base. The smallest number satisfying all these properties is sixty.
    – Lucian
    Oct 13, 2021 at 19:29

1 Answer 1


In a era when decimal numbers didn't exist, but fractions did, 60 has many factors: 1, 2, 3, 4, 5, 6, 10, 12, 15, 20, 30 and 60. The factors of 10 are: 1, 2, 5 and 10.

When dividing quantities into smaller units it is easier and more useful to be able to divide them into the smaller quantities if a base of 60 is used instead of 10.

  • 2
    Also, you can use your fingers to count. Use your thumb, and point your finger bone. You can count up to 12 (finger bone * 4 fingers). If you add one, put down one by going to the first finger bone, and carry one with one finger of the other hand. You have five fingers, 5*12 = 60
    – Kepotx
    Sep 17, 2020 at 6:48
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    @Kepotx, there's only one problem with your theory: the Mesopotamian sexagesimal system is based on 6*10, not 5*12.
    – Mark
    Sep 17, 2020 at 19:53
  • 1
    Also, 360 is close to the number of days in a year. Not sure it was relevant though. Jan 11, 2021 at 18:55

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