Should I mail the professor? Should I meet him in person? I am a MS student in CS who wishes to take a graduate level course in Statistics department. The course is Machine Learning and I did cover most of the prerequisite course's content in multiple undergraduate courses so I want him to waive the requirement. I have budget for only 10 courses and wish to complete this degree in 2 years. Taking these prerequisite course would mean that I cannot take other courses that interest me. 

The other reason I wish to have the requirement waived is because the course itself is a statistics department course which also has prerequisites statistic courses and my college only allows me to take 2 courses outside of our department.