The gon is a measurement of plane angles, corresponding to 1/400 of a full circle, thus dividing a right angle in 100. The unit is also known as the grad, grade or gradian. One gon is equal to 9/10 of a degree or π/200 of a radian.

One advantage of this unit of measurement is that if one is travelling on a course of 117 gon (clockwise from due North), say, then the direction to one's left is instantly convertible into 17 gons, while that to one's right is at 217 gons and that behind one is at 317 gons. A disadvantage is that the extremely common angles of 30° and 60° must be expressed in fractions.

The unit originated in France as the grade, as part of the all metric system. Due to confusion with existing grad(e) units of northern Europe, the name gon was adopted. In Germany, the unit is also known as the Neugrad (new degree).

Although attempts at a general introduction was made, the unit was really only adopted in some countries and for specialized areas, like land measurement. The French artillery has used the gon for decades. The familiar degree, 1/360 of a circle, or the mathematically convenient radian, 1/(2π) of a circle, (used in the SI system of units) are generally used instead of the gon.

External links

• Ask Dr Math

Gon is also the name of a manga series starring a small orange dinosaur named Gon; this character also appears in the video game Tekken 3.

Gon, the Little Fox is a famous Japanese childrens story by Nankichi Niimi.