The formal name is tricontakaihenagon. Most people, including mathematicians, will use 31-gon since that effectively communicates the size of the polygon. But, if you want to appear pretentious or be obfuscatory, by all means use the Greek prefices.
What is 31 sided polygon called
The name of a polygon with 15 sides is a pentadecagon
A pentagon is the polygon with 5 sides.
A polygon with seven sides is a heptagon.
A polygon can have any number of sides above three. The name of a three-sided polygon is a triangle.
A regular polygon
31!
Tricontakaihenagon
The name of a polygon with 15 sides is a pentadecagon
There is no formula for how many sides there are in a polygon; the name of the polygon shows how many sides it has.
A pentagon is the polygon with 5 sides.
A polygon with seven sides is a heptagon.
There is no name because such a polygon does not exist. A polygon must have at least three sides.
There is not a name for such a polygon. A polygon with one million sides is called a megagon though..
A polygon with 6 sides is called a hexagon.
A polygon with ten sides is a decagon.
the name of the polygon with 101 sides is hecatontakaihenagon
A polygon with 4 sides is a quadrilateral.