> Depends on how urgently you want to define a clearly useful, *existing* set of measuring tools as 'trivial,' of course. Bringing up the 10-hour day and 10-hour week is irrelevant -- and in fact, trivial -- because no one is seriously proposing to adopt "metric time" as a new standard! I guess a 400-degree circle is an interesting concept, however. Perhaps gremlinn could explain how the right angle was set at 90 degrees (rather than 100°) in the first place.
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It comes from the (quasi?) base-60 integer system used by the Sumerians (I knew the base-60 part, but had to look up which civilization it was). 60, of course, has the advantage of being divisible by a lot of small numbers (1, 2, 3, 4, 5, 6) without being too large itself. Put in an extra factor of 6 and you gain divisibility by 8, 9, and 10 as well. So, since there are 360 degrees in the circle, it's easy to subdivide the circle evenly into pieces with integral degree measures in a lot of ways. In the linked article, I have no idea what they mean by a "perfect system for geometry", though.

The angle measure of 1/400 of the circle is called the gradient (not to be confused with the gradient of multivariate calculus). I don't know where it is used, but my calculator converts between degrees, gradients, and radians.

Beyond the convenience of integral divisibility for geometrical purposes, there's no good reason to use degrees instead of radians. Using radians as your angle measurement makes formulas in trigonometry, calculus, and beyond come out nicely, instead of the conversion factor (pi/180) popping out as a multiplicative constant everywhere.