Total exterior angle of a polygon
To remember the total exterior angle of a polygon, you should take a pencil and run it around the outside of the polygon to see how many times it rotates. You will always find that it rotates once.
Therefore the total exterior angle of a polygon = 360° (always)
Notice how the pencil only makes one single turn before arriving back at its starting position.
This is true of any regular (all sides equal) and irregular sided polygon.