If a regular polygon has exterior angles that measure 40 degrees each, how many sides does the polygon have?

a. 10
b. 9
c. 6
d. 8

The measure of the exterior angle of a regular polygon is the quotient when a whole revolution, 360 degrees, is divided by the number of sides (n). This is shown in the equation, 
  
                                                A = 360 / n 
From the given above, 
                                          40 = 360 / n       ; n = 9

Therefore, the answer is letter B. 9.