Are domains with numbers given less authority in the eyes of a search engine? I'm trying to rank for an online course, and I was going to go with "Course101". Would it be better to go with "TheCourse"?
are you trying to rank for the keywords "Online Course"??? If so would be wise to use a domain something like this onlinecourse101.com . The numbers are ok. Better not to have them but they won't hurt much. Make sure you go for a .com or .net is much more important as they get ranked faster by Google.
do your keyword research, hours spent in kw research are paid back when you are trying to rank, get a kw rich domain and buid it from there, just make sure people are searching for those kw's in your domain