How many sides does a polygon have if it has 16 vertices?

Mark each vertice with a number, from 1 to 16... then shift each mark slightly in a clockwise direction and you will have 16 sides each marked from 1 to 16.

Every vertex in a polygon has an associated side, such that:

• a triangle has 3 angles and 3 sides
• a square has 4 angles and 4 sides
• a pentagon has 5 angles and 5 sides.

You cannot add a side to any of these without also adding an angle.