If you haven't noticed, each country has a different length of phone number, but there is a reason it's done that way. Here's ...

The numbers contain no meaning beyond that. In the example above, 11360 is the CRN for this course and section. The four-letter Course Prefix indicates the department or program offering the course.

Where <prefix> is the prefix to be added and <cell number of first cell> is the location of the first cell in the column to which to add the prefix. Eg. We are creating the list in column C.