When you draw a circle in SketchUp, it actually makes a 24 sided polygon.
I found that isn't always round enough to work as a circle.
I made this to contrast the different feelings of differently sided polygons.
1 Quarter is a 24 sided Polygon. (SketchUp default)
1 Quarter is a 36 sided Polygon.
1 Quarter is a 48 sided Polygon.
1 Quarter is a 96 sided Polygon.
Technically, that makes the bottom of this model an irregular 51 sided polygon.