A regular polygon is a polygon with equal angles and equal sides. To find the number of sides of a regular polygon, I need to use the formula: n = 360 / (180 - A), where n is the number of sides and A is the measure of each interior angle. In this case, A is 120 degrees, so I plug that into the formula: n = 360 / (180 - 120). This simplifies to n = 360 / 60, which is n = 6. Therefore, the regular polygon has 6 sides. 
A regular polygon has interior angles of 120 degrees. How many sides does the polygon have?