Marshall,
The main table that is a linked table is NAMEADDR. The table 1-9999 is for
Branch and Customer numbers in the fll range 1-9999. Because not all the
Branches use numbers all the way to 9999, some may stop at 7999, but I still
need the range to be 1-9999. What would I be pulling from the NAMEADDR table?

query  BranchNumbers:
SELECT [tbl 1-9999].[number], Branches.BranchNum
FROM NAMEADDR, Branches

OK, maybe this is what you want...

Piggybacking on Marshall's clever idea of using the Cartesian product of
a small Table with itself, I define a Table containing only 10 numbers:

[tbl 0-9] Table Datasheet View:

  number
  ------
  0
  1
  2
  3
  4
  5
  6
  7
  8
  9

I also have a Table that specifies the maximum number of accounts at
each Branch.  (I changed Branch "01" from 1680 to 998 to make the
example work better.  You should set them to whatever is correct.)

[Branches] Table Datasheet View:

  Branch    NumberOfAccounts
  ------    ----------------
  01        998
  02        997
  03        500
  04        74
  ...

And we have the Table of existing, and thus unavailable, account numbers
at each Branch.  I have included only two Branches, to make the example
more concise:

[NAMEADDR] Table Datasheet View:

  co-number cust-number
  --------- -----------
  01        993
  01        995
  01        996
  02        991
  02        995

Now we create a Query to list all 9999 possible customer numbers for any
Branch, including those that may be in use:

[Q_9999] SQL:

  SELECT [1000].number*1000+[100].number*100+[10].number*10
  +[1].number AS [Number]
  FROM [tbl 0-9] AS 1000, [tbl 0-9] AS 100, [tbl 0-9] AS 10,
  [tbl 0-9] AS 1
  WHERE ((([1000].[number]*1000+[100].[number]*100+[10].[number]*10
  +[1].[number])<>0))
  ORDER BY [1000].number*1000+[100].number*100
  +[10].number*10+[1].number;

(I expect that this occupies considerably less space than a
10,000-record Table.)  As you might expect, the contents are kind of
boring, and I've omitted most of them here:

[Q_9999] Query Datasheet View:

  Number
  ------
  1
  2
  3
  4
  5
  ...
  9997
  9998
  9999

Now I define a Query that lists all of the possible account numbers for
each Branch, up to the limit specified in [Branches].[NumberOfAccounts]:

[Q_Combo] SQL:

  SELECT Branches.Branch, Q_9999.Number
  FROM Branches, Q_9999
  WHERE (
  ((Branches.Branch)<="02") AND
  ((Q_9999.Number)<=[Branches]![NumberOfAccounts]
  And (Q_9999.Number)>=990
  ))
  ORDER BY Branches.Branch, Q_9999.Number;

The lines "((Branches.Branch)<="02") AND "
and "And (Q_9999.Number)>=990"
are included ONLY to make the example shorter.  You need to erase both
lines from this SQL.  This Query lists account numbers up to 998 for
Branch "01" and up to 997 for Branch "02", omitting the other numbers
and Branches.  The complete list, now, looks like this:

[Q_Combo] Query Datasheet View:

  Branch    number
  ------    ------
  01        990
  01        991
  01        992
  01        993
  01        994
  01        995
  01        996
  01        997
  01        998
  02        990
  02        991
  02        992
  02        993
  02        994
  02        995
  02        996
  02        997

Now we're ready to list the unused ones.  We define one more Query:

[Q_Unused] SQL:

  SELECT Q_Combo.Branch, Q_Combo.number
  FROM Q_Combo LEFT JOIN NAMEADDR
  ON (Q_Combo.Branch = NAMEADDR.[co-number])
  AND (Q_Combo.number = NAMEADDR.[cust-number])
  WHERE (((NAMEADDR.[co-number]) Is Null))
  ORDER BY Q_Combo.Branch, Q_Combo.number;

and -- voilá -- we have what I think you asked for, a list of all the
account numbers (up to the maximum allowed for each Branch) that are not
already listed in [NAMEADDR]:

[Q_Unused] Query Datasheet View:

  Branch    number
  ------    ------
  01        990
  01        991
  01        992
  01        994
  01        997
  01        998
  02        990
  02        992
  02        993
  02        994
  02        996
  02        997

Notice that account 995 is not listed for either Branch, but 993 is
listed for Branch "02".

  -- Vincent Johns <vjohns@alumni.caltech.edu>
  Please feel free to quote anything I say here.