Account numbers have an elegance that only an accountant could love. In systems that allow good use of numbering they can help categorize information in a variety of ways. Do you want to know which activity is most profitable in your organization? Use a part of your account number for activity and you can get reports sorted and summarized by that part. Here's an example from a Massachusetts town:
FFF-DDD-TAAA-YY##
where:
FFF = fund such as general fund, library incentive grant fund, community policing fund ...
DDD = department, further the first D denotes type, general, public safety, school, highway ...
TGAA = Type = 1 for assets, 2 for liabilities, 3 for equity, 5 for expense, 6 for prior year expense; G = 1 for personnel expense, 2 for contracted expense, ...
YY= year
## = number, may be a grant number, may be an article from town meeting number
001-210-5100-0000
general fund, police department, salaries, no detail
Now you can get all the accounts with 51 in type and group and get all your personnel costs across all departments and funds. If you wanted only the general fund you would get a listing of all accounts that were = 001-???-51??-????. If you wanted only public safety expense you would print a listing for ???=2??-5???-????. Suppose you wanted income and expense for the police department you would list accounts = ???-210-????-????.
Another reason for account numbers is that for accountants it keeps the right hand on the number keypad more making data entry faster. If you want to slow things down make accounts with both upper and lower case letters, numbers and symbols!