You have what's called a magician's coin. Please see the related question for more information.
2
NO sides stay the same every quarter at the begging the defending team picks the side
First Quarter and/or Third Quarter.
The name is "ERROR". A decagon cannot have 11 sides.
The truncation error is the difference between two sides of an equation. Each side has an error value which can be compared.
It's not exactly clear what you mean by "no sides" If you mean that the outer nickel-colored cladding is missing, leaving the inner copper core visible, that's called a lamination error and could be worth about $10. A lamination-error coin should be quite a bit thinner and lighter than a normal quarter. If not, i.e. it's the same thickness and weight as a normal quarter, it's either been plated or exposed to a chemical that changed its color, and is only worth 25c. If I didn't interpret your question correctly, please post a new one with more details.
There are several possible answers, but it would be most instructive to name eight figures having eight different numbers of sides. 1 side - not possible 2 sides - not possible 3 sides - triangle 4 sides - square, rectangle, rhombus, trapezoid 5 sides - pentagon 6 sides - hexagon 7 sides - septagon 8 sides - octagon 9 sides - nonagon 10 sides - decagon There are other possible answers for a four sided figure.
A circle as it has infinite number of sides
A polygon with the least number of sides is a triangle (3 sides)
The number of sides possible in a polygon is a minimum of 3, with an unlimited maximum. For a regular polygon, as the number of sides approaches infinity, it approaches the shape of a circle.
yes because a quarter has 2 sides but flipping it you dont have a 100%chance if it lands on the same side
They cost about $8 in novelty shops.