I use a custom format to display job numbers in the format YY-NNN, where Y is the year and N is an incrementing number. The first five jobs for this year look like this:
Note, however, that the formula bar shows the number 1, not the text displayed in the cell. The custom number format looks like this:
There are some advantages to having identifying numbers be actual numbers instead of text. For instance, I use a formula that finds the largest job number that has a description.
It’s a lot easier to do that with numerics because MAX would return zero if all the job numbers were text. For more information on custom formatting codes, see Create a Custom Number Format in help.