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Posted to microsoft.public.excel.misc,microsoft.public.excel.programming,microsoft.public.excel.worksheet.functions,microsoft.public.excel.newusers
Bill Martin
 
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Default find sum in list of of numbers

I do like your Solver approach -- I hadn't thought of that. Given that this is
an Accounting problem though, how would one get Solver to identify multiple
solutions to the problem when they exist? If you're trying to match invoices
you'd like to know that you're matching them correctly -- not just *possibly*
correctly. Which requires a person to stare at *all* the various possible
solutions and decide which one is most likely given some knowledge of the
customers involved and what they've ordered in the past, etc.

For example, take the list of 10 values that Dza provided and use them all twice
to make 20 entries. Now there are 8 valid solutions, but Solver only seems to
find one and stops.

Personally, I think you need VBA for this problem but I'm open to education...

Bill
----------------------------------
Ron Coderre wrote:
Have you tried using Excel Solver

First a little prep work....

A1:A1 (your list of values)
B1:B10 (leave blank)
C1: =A1*B1
(copy that fomula down through C10

C11: =SUM(C1:C10)

Now to use Solver....
ToolsSolver
Set Cell: C11
Equal to the Value of: 1173.76
By Changing Cells: B1:B10
Subject to the Constraints....
(click the add button and constrain B1:B10 to Binary)
Click [OK]
Click [Solve]

Excel will toggle cells B1:B10 between 1 and 0 until it comes up with a
combination that sums to 1,173.76

Does that help?

***********
Regards,
Ron

XL2002, WinXP-Pro


"Dave O" wrote:


The answer is:
$725.90
$240.16
$207.70

I've written a program that applies a brute force approach to the task-
it checks every possible combination of the "pool" of numbers to arrive
at the target total. The brute force idea works for comparatively
small pools, but since the number of possible combinations doubles with
each additional pool member the processing time increases
commensurately. One poster to this newsgroup wanted to process a list
of 100 numbers, which amounts to
1,267,650,600,228,230,000,000,000,000,000 possible combinations and
would require the resources of a major government (or maybe just the
NSA) to process.

How many of these do you have? I don't mind doing a few for you.