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Every scientific calculator I've come across has a DRG button that controls whether trigonometric functions use units of degrees, radians or grads yet I've never seen or heard of any system that actually uses grads. When is the grads setting useful?

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    $\begingroup$ all grad would do is rescale the angle to/from 0-400 instead of 0-2pi or 0-360, doesn't need that much more circuitry $\endgroup$ – ratchet freak Jun 22 '15 at 12:36
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    $\begingroup$ Blame Napoleon ................ $\endgroup$ – Russell McMahon Jun 22 '15 at 20:21
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Grads were developed by the French as part of the metric system and have been referred to as the metric degree.

In some countries in Europe surveyors use grads instead of degrees. The other use is by French artillery units who have used grads for decades.

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  • $\begingroup$ I was watching Guns of Navarone - near the end the German officer said neunzig grads when lining up the guns. I wonder whether that was really grads as grads in German means degrees. $\endgroup$ – cup Dec 28 '17 at 6:41
  • $\begingroup$ It is not just in Europe or artillery. It is common used at Survey, Civil Works... The key of the gradians is that they have a continuous numeration, they are not working on 60 units ranges so, 1 degree have 100 minutes on it and 1 minute have 100 seconds. So 357.6454 grad is 357 degres 64 minutes and 54 seconds. In computation, it is much simplier to work with Gradians than with Sexag. degrees. $\endgroup$ – David García Bodego Sep 22 at 7:38
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Gradians are commonly used in land surveying. I only know this because I made the mistake of asking the same question of a Civil Engineer.

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    $\begingroup$ Just interested: which country is that in? $\endgroup$ – cup Jun 23 '15 at 6:41
  • $\begingroup$ It was when I was an undergrad. I only recall asking the question in general and getting a much more detailed answer than I really ever wanted. Professionally, as a ME, I've never used grads, nor even seen them used. My understanding was that they were used by surveyors in the field, but typically converted to DMS before passing measurements along. $\endgroup$ – DLS3141 Jun 23 '15 at 14:14
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Grade is often used for inclination, such as looking at how steep a road is. The units are not as "crazy" as they seem, when you think of grade as a percentage. In other words, a hill can go down at anything from 0% (flat) to 100% (45 deg angle). (rise/run) Based on some comments added below, it is not clear if the G on this calculator is actually grade or not.

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  • $\begingroup$ This interpretation has major issues outside of the first quadrant. (For instance, how should you expect 50%, 150% and 250% to compare?) There is also the problem that "100% grade" in roadway terms means equal rise-per-run, or a 45° angle (rather than a cliff). $\endgroup$ – Air Jun 22 '15 at 19:21
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    $\begingroup$ You are mistaking gradians for gradient. As @Air said, 100% gradient corresponds to 50 gradians. $\endgroup$ – Erik Olson Jun 22 '15 at 19:37

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