What is the measure of each exterior angle of a regular 90-gon?

To find the measure of each exterior angle of a regular polygon, you can use the formula ( \frac{360^\circ}{n} ), where ( n ) is the number of sides. For a regular 90-gon, this gives ( \frac{360^\circ}{90} = 4^\circ ). Therefore, each exterior angle of a regular 90-gon measures 4 degrees.