# Gradian

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Unit of measurement of an angle, equal to 1/400th of a circle

"Grade (angle)" redirects here. For the grade of an inclined surface, see [Grade (slope)](/source/Grade_(slope)).

"Gon (angle)" redirects here. For n-gon, see [Regular polygon](/source/Regular_polygon).

Not to be confused with [Gradient](/source/Gradient).

gon Compass graded with 400 gon General information Unit of Angle Symbol gon, ᵍ, grad Conversions 1 gon in ... ... is equal to ... turns ⁠1/400⁠ turn radians ⁠π/200⁠ rad ≈ 0.0157... rad milliradians 5π mrad ≈ 15.71... mrad degrees 0.9° minutes of arc 54′

In [trigonometry](/source/Trigonometry), the **gradian** – also known as the **gon** (from [Ancient Greek](/source/Ancient_Greek_language) [γωνία](https://en.wiktionary.org/wiki/%CE%B3%CF%89%CE%BD%CE%AF%CE%B1#Ancient_Greek)*(*gōnía*)* 'angle'), **grad**, or **grade**[1] – is a [unit of measurement](/source/Unit_of_measurement) of an [angle](/source/Angle), defined as one-hundredth of the [right angle](/source/Right_angle); in other words, 100 gradians is equal to 90 degrees.[2][3][4] It is equivalent to ⁠1/400⁠ of a [turn](/source/Turn_(geometry)),[5] ⁠9/10⁠ of a [degree](/source/Degree_(angle)), or ⁠π/200⁠ of a [radian](/source/Radian). Measuring angles in gradians (gons) is said to employ the *centesimal* system of angular measurement, initiated as part of [metrication](/source/Metrication) and [decimalisation](/source/Decimalisation) efforts.[6][7][8][a]

In continental [Europe](/source/Europe), the French word ***centigrade***, also known as *centesimal minute of arc*, was in use for one hundredth of a grade; similarly, the *centesimal second of arc* was defined as one hundredth of a centesimal arc-minute, analogous to [decimal time](/source/Decimal_time) and the [sexagesimal](/source/Sexagesimal_degrees) [minutes and seconds of arc](/source/Minutes_and_seconds_of_arc).[12] The chance of confusion was one reason for the adoption of the term *[Celsius](/source/Celsius)* to replace *centigrade* as the name of the temperature scale.[13][14]

Gradians (gons) are principally used in [surveying](/source/Surveying) (especially in Europe),[15][7][16] and to a lesser extent in [mining](/source/Mining)[17] and [geology](/source/Geology).[18][19]

The gon (gradian) is a legally recognised unit of measurement in the [European Union](/source/European_Union)[20]: 9 and in [Switzerland](/source/Switzerland).[21] However, this unit is not part of the [International System of Units](/source/International_System_of_Units) (SI).[22][20]: 9–10

## History and name

The unit originated in [France](/source/France) in connection with the [French Revolution](/source/French_Revolution) as the *grade*, along with the [metric system](/source/Metric_system), hence it is occasionally referred to as a *metric degree*. Due to confusion with the existing term *grad(e)* in some northern European countries (meaning a standard degree, ⁠1/360⁠ of a turn), the name *gon* was later adopted, first in those regions, and later as the international standard.[*[which?](https://en.wikipedia.org/wiki/Wikipedia:Avoid_weasel_words)*] In France, it was also called *grade nouveau*. In [German](/source/German_language), the unit was formerly also called *Neugrad* (new degree) (whereas the standard degree was referred to as *Altgrad* (old degree)), likewise *nygrad* in [Danish](/source/Danish_language), [Swedish](/source/Swedish_language) and [Norwegian](/source/Norwegian_language) (also *gradian*), and *nýgráða* in [Icelandic](/source/Icelandic_language).

Although attempts at a general introduction were made, the unit was only adopted in some countries, and for specialised areas such as [surveying](/source/Surveying),[15][7][16] [mining](/source/Mining)[17] and [geology](/source/Geology).[18][19] Today, the degree, ⁠1/360⁠ of a [turn](/source/Turn_(geometry)), or the mathematically more convenient [radian](/source/Radian), ⁠1/2π⁠ of a turn (used in the [SI](/source/SI) system of units) is generally used instead.

In the 1970s –1990s, most [scientific calculators](/source/Scientific_calculator) offered the gon (gradian), as well as radians and degrees, for their [trigonometric functions](/source/Trigonometric_functions).[23] In the 2010s, some scientific calculators lack support for gradians.[24]

### Symbol

◌ᵍo Gon In Unicode U+1D4D ᵍ MODIFIER LETTER SMALL G Related See also U+00B0 ° DEGREE SIGN

The international standard symbol for this unit is "gon" (see [ISO 31-1](/source/ISO_31-1), Annex B).[*[needs update](https://en.wikipedia.org/wiki/Wikipedia:Manual_of_Style/Dates_and_numbers#Chronological_items)*] Other symbols used in the past include "gr", "grd", and "g", the last sometimes written as a superscript, similarly to a degree sign: 50g = 45°. A [metric prefix](/source/Metric_prefix) is sometimes used, as in "dgon", "cgon", "mgon", denoting respectively 0.1 gon, 0.01 gon, 0.001 gon. Centesimal arc-minutes and centesimal arc-seconds were also denoted with superscripts c and cc, respectively.

SI multiples of gon (gon) Submultiples Multiples Value SI symbol Name Value SI symbol Name 10−1 gon dgon decigon 101 gon dagon decagon 10−2 gon cgon centigon 102 gon hgon hectogon 10−3 gon mgon milligon 103 gon kgon kilogon 10−6 gon μgon microgon 106 gon Mgon megagon 10−9 gon ngon nanogon 109 gon Ggon gigagon 10−12 gon pgon picogon 1012 gon Tgon teragon 10−15 gon fgon femtogon 1015 gon Pgon petagon 10−18 gon agon attogon 1018 gon Egon exagon 10−21 gon zgon zeptogon 1021 gon Zgon zettagon 10−24 gon ygon yoctogon 1024 gon Ygon yottagon 10−27 gon rgon rontogon 1027 gon Rgon ronnagon 10−30 gon qgon quectogon 1030 gon Qgon quettagon

## Advantages and disadvantages

Each quadrant is assigned a range of 100 gon, which eases recognition of the four quadrants, as well as arithmetic involving perpendicular or opposite angles.

- 0° = 0 gradians 90° = 100 gradians 180° = 200 gradians 270° = 300 gradians 360° = 400 gradians

One advantage of this unit is that right angles to a given angle are easily determined. If one is sighting down a compass course of 117 gon, the direction to one's left is 17 gon, to one's right 217 gon, and behind one 317 gon. A disadvantage is that the common angles of 30° and 60° in geometry must be expressed in fractions (as ⁠33+1/3⁠ gon and ⁠66+2/3⁠ gon respectively).

## Conversion

Conversion of common angles Turns Radians Degrees Gradians 0 turn 0 rad 0° 0g ⁠1/72⁠ turn ⁠π/36⁠ or ⁠𝜏/72⁠ rad 5° ⁠5+5/9⁠g ⁠1/24⁠ turn ⁠π/12⁠ or ⁠𝜏/24⁠ rad 15° ⁠16+2/3⁠g ⁠1/16⁠ turn ⁠π/8⁠ or ⁠𝜏/16⁠ rad 22.5° 25g ⁠1/12⁠ turn ⁠π/6⁠ or ⁠𝜏/12⁠ rad 30° ⁠33+1/3⁠g ⁠1/10⁠ turn ⁠π/5⁠ or ⁠𝜏/10⁠ rad 36° 40g ⁠1/8⁠ turn ⁠π/4⁠ or ⁠𝜏/8⁠ rad 45° 50g ⁠1/2π or 𝜏⁠ turn 1 rad approx. 57.3° approx. 63.7g ⁠1/6⁠ turn ⁠π/3⁠ or ⁠𝜏/6⁠ rad 60° ⁠66+2/3⁠g ⁠1/5⁠ turn ⁠2π or 𝜏/5⁠ rad 72° 80g ⁠1/4⁠ turn ⁠π/2⁠ or ⁠𝜏/4⁠ rad 90° 100g ⁠1/3⁠ turn ⁠2π or 𝜏/3⁠ rad 120° ⁠133+1/3⁠g ⁠2/5⁠ turn ⁠4π or 2𝜏 or α/5⁠ rad 144° 160g ⁠1/2⁠ turn π or ⁠𝜏/2⁠ rad 180° 200g ⁠3/4⁠ turn ⁠3π or ρ/2⁠ or ⁠3𝜏/4⁠ rad 270° 300g 1 turn 𝜏 or 2π rad 360° 400g

## Relation to the metre

Further information: [History of the metre § Meridional definition](/source/History_of_the_metre#Meridional_definition)

See also: [Arc length § Great circles on Earth](/source/Arc_length#Great_circles_on_Earth), and [Nautical mile § Similar definitions](/source/Nautical_mile#Similar_definitions)

An early definition of the [metre](/source/Metre) was one ten-millionth of the distance from the [North Pole](/source/North_Pole) to the [equator](/source/Equator), measured along a [meridian](/source/Meridian_(geography)) through [Paris](/source/Paris).

In the 18th century, the [metre](/source/Metre) was defined as the 10-millionth part of a [quarter meridian](/source/Quarter_meridian). Thus, 1 gon corresponds to an [arc length](/source/Arc_length) along the Earth's surface of approximately 100 kilometres; 1 centigon to 1 kilometre; 10 microgons to 1 metre.[25] (The [metre has been redefined](/source/Metre#History_of_definition) with increasing precision since then.)

## Relation to the SI system of units

The gradian is *not* part of the [International System of Units](/source/International_System_of_Units) (SI). The EU directive on the units of measurement[20]: 9–10 notes that the gradian "does not appear in the lists drawn up by the [CGPM](/source/General_Conference_on_Weights_and_Measures), [CIPM](/source/General_Conference_on_Weights_and_Measures#CIPM) or [BIPM](/source/International_Bureau_of_Weights_and_Measures)." The most recent, 9th edition of the [SI Brochure](/source/International_System_of_Units#SI_Brochure) does not mention the gradian at all.[22] The previous edition mentioned it only in the following footnote:[26]

The gon (or grad, where grad is an alternative name for the gon) is an alternative unit of plane angle to the degree, defined as (π/200) rad. Thus there are 100 gon in a right angle. The potential value of the gon in navigation is that because the distance from the pole to the equator of the Earth is approximately 10000 km, 1 km on the surface of the Earth subtends an angle of one centigon at the centre of the Earth. However the gon is rarely used.

## See also

- [Angular frequency](/source/Angular_frequency) – Rate of change of angle

- [Milliradian](/source/Milliradian) – Angular measurement, thousandth of a radian (primarily military use)

- [Harmonic analysis](/source/Harmonic_analysis) – Area of mathematical analysis

- [Jean-Charles de Borda](/source/Jean-Charles_de_Borda) – French scientist and Navy officer (1733–1799)

- [Repeating circle](/source/Repeating_circle) – Type of angular measurement instrument

- [Spread (rational trigonometry)](/source/Spread_(rational_trigonometry)) – 2005 book reformulating plane geometryPages displaying short descriptions of redirect targets

- [Steradian](/source/Steradian) – SI derived unit of solid angle (the "square radian")

## Notes

1. **[^](#cite_ref-12)** On rare occasions, *centesimal* refers to the division of the full angle (360°) into hundred parts. One example is the description of the gradations on [Georg Ohm](/source/Georg_Ohm)'s torsion balance in a history of physics book from 1899.[9] The gradations were in one-hundredths of a full revolution.[10][11]

## References

1. **[^](#cite_ref-1)** Weisstein, Eric W. ["Gradian"](https://mathworld.wolfram.com/Gradian.html). *mathworld.wolfram.com*. Retrieved 2020-08-31.

1. **[^](#cite_ref-handbookOfMath_2-0)** Harris, J. W.; Stocker, H. (1998). *Handbook of Mathematics and Computational Science*. New York: [Springer-Verlag](/source/Springer-Verlag). p. 63.

1. **[^](#cite_ref-3)** ["NIST Guide to the SI, Appendix B.9: Factors for units listed by kind of quantity or field of science"](https://web.archive.org/web/20170417071705/https://www.nist.gov/pml/nist-guide-si-appendix-b9-factors-units-listed-kind-quantity-or-field-science). *nist.gov*. [NIST](/source/National_Institute_of_Standards_and_Technology). Archived from [the original](https://nist.gov/pml/nist-guide-si-appendix-b9-factors-units-listed-kind-quantity-or-field-science#ANGLE) on 2017-04-17.

1. **[^](#cite_ref-4)** Patrick Bouron (2005). [*Cartographie: Lecture de Carte*](https://web.archive.org/web/20100415034329/http://webdav-noauth.unit-c.fr/files/perso/pbarbier/cours_unit/Elements_de_base_de_la_cartographie.pdf) (PDF). Institut Géographique National. p. 12. Archived from [the original](http://webdav-noauth.unit-c.fr/files/perso/pbarbier/cours_unit/Elements_de_base_de_la_cartographie.pdf) (PDF) on 2010-04-15. Retrieved 2011-07-07.

1. **[^](#cite_ref-5)** ["Gradian"](https://artofproblemsolving.com/wiki/index.php/Gradian). *Art of Problem Solving*. Retrieved 2020-08-31.

1. **[^](#cite_ref-Balzer_1946_6-0)** Balzer, Fritz (1946). [*Five Place Natural Sine and Tangent Functions in the Centesimal System*](https://books.google.com/books?id=2IxG7M9Yw0UC&q=centesimal&pg=PP9). Army Map Service, Corps of Engineers, U.S. Army.

1. ^ [***a***](#cite_ref-Zimmerman_7-0) [***b***](#cite_ref-Zimmerman_7-1) [***c***](#cite_ref-Zimmerman_7-2) Zimmerman, Edward G. (1995). ["6. Angle Measurement: Transits and Theodolites"](https://books.google.com/books?id=2gB7w9XlNJAC&q=centesimal&pg=PA80). In Minnick, Roy; Brinker, Russell Charles (eds.). *The surveying handbook* (2nd ed.). Chapman & Hall. [ISBN](/source/ISBN_(identifier)) [041298511X](https://en.wikipedia.org/wiki/Special:BookSources/041298511X).

1. **[^](#cite_ref-Gorini_2003_8-0)** Gorini, Catherine A. (2003). [*The Facts on File Geometry Handbook*](https://books.google.com/books?id=PlYCcvgLJxYC). Infobase Publishing. p. [22](https://books.google.com/books?id=PlYCcvgLJxYC&q=centesimal&pg=PA22). [ISBN](/source/ISBN_(identifier)) [978-1-4381-0957-2](https://en.wikipedia.org/wiki/Special:BookSources/978-1-4381-0957-2).

1. **[^](#cite_ref-Cajori_1899_9-0)** Cajori, Florian (1899). [*A History of Physics in Its Elementary Branches: Including the Evolution of Physical Laboratories*](https://books.google.com/books?id=7Y5KAAAAMAAJ&dq=%22history%22%20centesimal%20angle&pg=PA229). Macmillan. [ISBN](/source/ISBN_(identifier)) [9781548494957](https://en.wikipedia.org/wiki/Special:BookSources/9781548494957). The angle through which the torsion-head must be deflected was measured in centesimal divisions of the circle {{[cite book](https://en.wikipedia.org/wiki/Template:Cite_book)}}: ISBN / Date incompatibility ([help](https://en.wikipedia.org/wiki/Help:CS1_errors#invalid_isbn_date))

1. **[^](#cite_ref-Ohm_1826_10-0)** Ohm, Georg Simon (1826). ["Bestimmung des Gesetzes, nach welchem Metalle die Contactelektricität leiten, nebst einem Entwurfe zur Theorie des Voltaischen Apparates und des Schweiggerschen Multiplikators"](https://web.archive.org/web/20200523161946/http://www2.ohm-hochschule.de/bib/textarchiv/Ohm.Bestimmung_des_Gesetzes.pdf) (PDF). *Journal für Chemie und Physik*. **46**: 137–166. Archived from [the original](http://www2.ohm-hochschule.de/bib/textarchiv/Ohm.Bestimmung_des_Gesetzes.pdf) (PDF) on 23 May 2020. [German](/source/German_language): *wurde die Größe der Drehung oben an der Drehwage in Hunderttheilen einer ganzen Umdrehung abgelesen* (p. 147) [the amount of rotation at the top of the torsion balance was read in hundred parts of an entire revolution]

1. **[^](#cite_ref-Keithley_1999_11-0)** Keithley, Joseph F. (1999). [*The Story of Electrical and Magnetic Measurements: From 500 BC to the 1940s*](https://www.google.com/search?tbm=bks&q=%22It+hung+on+a+ribbon+torsion+element+with+a+knob+on+top%2C+graduated+in+100+parts.%22). John Wiley & Sons. [ISBN](/source/ISBN_(identifier)) [978-0-7803-1193-0](https://en.wikipedia.org/wiki/Special:BookSources/978-0-7803-1193-0). It hung on a ribbon torsion element with a knob on top, graduated in 100 parts.

1. **[^](#cite_ref-Klein_2012_p._114_13-0)** Klein, H.A. (2012). [*The Science of Measurement: A Historical Survey*](https://books.google.com/books?id=CrmuSiCFyikC&pg=PA114). Dover Books on Mathematics. Dover Publications. p. 114. [ISBN](/source/ISBN_(identifier)) [978-0-486-14497-9](https://en.wikipedia.org/wiki/Special:BookSources/978-0-486-14497-9). Retrieved 2022-01-02.

1. **[^](#cite_ref-14)** Frasier, E. Lewis (February 1974), "Improving an imperfect metric system", *Bulletin of the Atomic Scientists*, **30** (2): 9–44, [Bibcode](/source/Bibcode_(identifier)):[1974BuAtS..30b...9F](https://ui.adsabs.harvard.edu/abs/1974BuAtS..30b...9F), [doi](/source/Doi_(identifier)):[10.1080/00963402.1974.11458078](https://doi.org/10.1080%2F00963402.1974.11458078). On [p. 42](https://books.google.com/books?id=IwwAAAAAMBAJ&pg=PA42) Frasier argues for using grads instead of radians as a standard unit of angle, but for renaming grads to "radials" instead of renaming the temperature scale.

1. **[^](#cite_ref-15)** Mahaffey, Charles T. (1976), ["Metrication problems in the construction codes and standards sector"](https://archive.org/stream/metricationprobl915maha), *Final Report National Bureau of Standards*, NBS Technical Note 915, U.S. Department of Commerce, National Bureau of Commerce, Institute for Applied Technology, Center for Building Technology, [Bibcode](/source/Bibcode_(identifier)):[1976nbs..reptU....M](https://ui.adsabs.harvard.edu/abs/1976nbs..reptU....M), The term "Celsius" was adopted instead of the more familiar "centigrade" because in France the word centigrade has customarily been applied to angles.

1. ^ [***a***](#cite_ref-Kahmen_and_Faig_2012_16-0) [***b***](#cite_ref-Kahmen_and_Faig_2012_16-1) Kahmen, Heribert; Faig, Wolfgang (2012). [*Surveying*](https://books.google.com/books?id=7nMiAAAAQBAJ&dq=%22gon%22%20%20%22surveying%22%20%22Europe%22&pg=PA58). De Gruyter. [ISBN](/source/ISBN_(identifier)) [9783110845716](https://en.wikipedia.org/wiki/Special:BookSources/9783110845716).

1. ^ [***a***](#cite_ref-Schofield_17-0) [***b***](#cite_ref-Schofield_17-1) Schofield, Wilfred (2001). [*Engineering surveying: theory and examination problems for students*](https://books.google.com/books?id=1wYBMUYV0b0C&q=gon&pg=PA23) (5th ed.). Butterworth-Heinemann. [ISBN](/source/ISBN_(identifier)) [9780750649872](https://en.wikipedia.org/wiki/Special:BookSources/9780750649872).

1. ^ [***a***](#cite_ref-Sroka_18-0) [***b***](#cite_ref-Sroka_18-1) Sroka, Anton (2006). ["Contribution to the prediction of ground surface movements caused by a rising water level in a flooded mine"](https://books.google.com/books?id=-smnDwAAQBAJ&q=gon&pg=PA68). In Sobczyk, Eugeniusz; Kicki, Jerzy (eds.). *International Mining Forum 2006, New Technological Solutions in Underground Mining: Proceedings of the 7th International Mining Forum, Cracow - Szczyrk - Wieliczka, Poland, February 2006*. [CRC Press](/source/CRC_Press). [ISBN](/source/ISBN_(identifier)) [9780415889391](https://en.wikipedia.org/wiki/Special:BookSources/9780415889391).

1. ^ [***a***](#cite_ref-Gunzburger_et_al._2004_19-0) [***b***](#cite_ref-Gunzburger_et_al._2004_19-1) Gunzburger, Yann; Merrien-Soukatchoff, Véronique; Senfaute, Gloria; Piguet, Jack-Pierre; Guglielmi, Yves (2004). ["Field investigations, monitoring and modeling in the identification of rock fall causes"](https://books.google.com/books?id=DLPNBQAAQBAJ&dq=mining%20measurement%20%22gon%22%20-%22data%20mining%22&pg=PA561). In Lacerda, W.; Ehrlich, Mauricio; Fontoura, S. A. B.; Sayão, A. S. F. (eds.). *Landslides: Evaluation & Stabilization/Glissement de Terrain: Evaluation et Stabilisation, Set of 2 Volumes: Proceedings of the Ninth International Symposium on Landslides, June 28 -July 2, 2004 Rio de Janeiro, Brazil*. Vol. 1. CRC Press. [ISBN](/source/ISBN_(identifier)) [978-1-4822-6288-9](https://en.wikipedia.org/wiki/Special:BookSources/978-1-4822-6288-9).

1. ^ [***a***](#cite_ref-Schmidt_and_Kühn_2007_20-0) [***b***](#cite_ref-Schmidt_and_Kühn_2007_20-1) Schmidt, Dietmar; Kühn, Friedrich (2007). ["3. Remote sensing: 3.1 Aerial Photography"](https://books.google.com/books?id=QF5_Xvhm8KQC&dq=geology%20%22gon%22&pg=PA28). In Knödel, Klaus; Lange, Gerhard; Voigt, Hans-Jürgen (eds.). *Environmental Geology: Handbook of Field Methods and Case Studies*. [Springer Science & Business Media](/source/Springer_Science_%26_Business_Media). [ISBN](/source/ISBN_(identifier)) [978-3-540-74671-3](https://en.wikipedia.org/wiki/Special:BookSources/978-3-540-74671-3).

1. ^ [***a***](#cite_ref-EU_units_21-0) [***b***](#cite_ref-EU_units_21-1) [***c***](#cite_ref-EU_units_21-2) ["Directive 80/181/EEC"](https://web.archive.org/web/20200522202337/https://eur-lex.europa.eu/legal-content/EN/TXT/PDF/?uri=CELEX%3A01980L0181-20090527&from=EN). 27 May 2009. Archived from [the original](https://eur-lex.europa.eu/legal-content/EN/TXT/PDF/?uri=CELEX:01980L0181-20090527&from=EN) on 22 May 2020. On the approximation of the laws of the Member States relating to units of measurement and on the repeal of Directive 71/354/EEC.

1. **[^](#cite_ref-Switzerland_units_22-0)** ["941.202 Einheitenverordnung"](https://web.archive.org/web/20200522202750/https://www.admin.ch/opc/de/classified-compilation/19940345/) (in German). Archived from [the original](https://www.admin.ch/opc/de/classified-compilation/19940345/) on 22 May 2020.

1. ^ [***a***](#cite_ref-SI_Brochure_9th_ed_23-0) [***b***](#cite_ref-SI_Brochure_9th_ed_23-1) [*The International System of Units*](https://www.bipm.org/documents/20126/41483022/SI-Brochure-9-EN.pdf) (PDF), V4.01 (9th ed.), International Bureau of Weights and Measures, Jun 2026, [ISBN](/source/ISBN_(identifier)) [978-92-822-2272-0](https://en.wikipedia.org/wiki/Special:BookSources/978-92-822-2272-0)

1. **[^](#cite_ref-24)** Maloney, Timothy J. (1992), [*Electricity: Fundamental Concepts and Applications*](https://archive.org/details/electricityfunda0000malo/page/453), Delmar Publishers, p. [453](https://archive.org/details/electricityfunda0000malo/page/453), [ISBN](/source/ISBN_(identifier)) [9780827346758](https://en.wikipedia.org/wiki/Special:BookSources/9780827346758), On most scientific calculators, this [the unit for angles] is set by the DRG key

1. **[^](#cite_ref-25)** Cooke, Heather (2007), [*Mathematics for Primary and Early Years: Developing Subject Knowledge*](https://books.google.com/books?id=C3t4B3stB0UC&pg=PA53), SAGE, p. 53, [ISBN](/source/ISBN_(identifier)) [9781847876287](https://en.wikipedia.org/wiki/Special:BookSources/9781847876287), Scientific calculators commonly have two modes for working with angles – degrees and radians

1. **[^](#cite_ref-26)** [Cartographie – lecture de carte – Partie H Quelques exemples à retenir](http://webdav-noauth.unit-c.fr/files/perso/pbarbier/cours_unit/Elements_de_base_de_la_cartographie.pdf). [Archived](https://web.archive.org/web/20120302111251/http://webdav-noauth.unit-c.fr/files/perso/pbarbier/cours_unit/Elements_de_base_de_la_cartographie.pdf) 2 March 2012 at the [Wayback Machine](/source/Wayback_Machine).

1. **[^](#cite_ref-SI_Brochure_8th_ed_27-0)** [International Bureau of Weights and Measures](/source/International_Bureau_of_Weights_and_Measures) (2006), [*The International System of Units (SI)*](https://www.bipm.org/documents/20126/41483022/si_brochure_8.pdf) (PDF) (8th ed.), [ISBN](/source/ISBN_(identifier)) [92-822-2213-6](https://en.wikipedia.org/wiki/Special:BookSources/92-822-2213-6), [archived](https://web.archive.org/web/20210604163219/https://www.bipm.org/documents/20126/41483022/si_brochure_8.pdf) (PDF) from the original on 2021-06-04, retrieved 2021-12-16

## External links

- [Ask Dr Math](http://mathforum.org/library/drmath/view/55451.html)

- Definitions of [grade](http://www.sizes.com/units/grade.htm), [gon](http://www.sizes.com/units/gon.htm) and [centigrade](http://www.sizes.com/units/temperature_centigrade.htm) on sizes.com

- [Dictionary of Units](http://www.cleavebooks.co.uk/dictunit/notesa.htm)

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