I found out my number from the TV in my dorm lobby. (McCollum Hall). My number might have been high enough to keep me out but my home county (Doniphan) had a small population.
I enlisted in the Navy to avoid the Army and spent the next four years in California and Alaska. As I told my father (WWII Combat Vet) afterwards: "I always had a bunk to sleep in and three meals a day, and no one ever shot at me!"
p.s. My brother lived in the same dorm and his number was high. He did not have to join the service.