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Find which numbers sum up to given total

  1. #1
    Keith Cunningham
    Guest

    Find which numbers sum up to given total

    I have been presented with 13 numbers and given a total for the sum of
    5 of these numbers. Will excel allow me to find which 5 of the given
    numbers add up to my known total.



  2. #2
    Herbert Seidenberg
    Guest

    Re: Find which numbers sum up to given total

    Sub add_perm()
    Dim i As Integer
    Dim j As Integer
    Dim k As Integer
    Dim m As Integer
    Dim n As Integer
    Dim p As Integer
    Dim NN As Integer
    Dim SS As Integer

    Range("destination").ClearContents
    SS = Range("known_total")
    NN = Range("numbers") - 1 '13-1

    p = 1

    For i = 0 To NN
    For j = 0 To NN
    For k = 0 To NN
    For m = 0 To NN
    For n = 0 To NN
    If Not (i >= j Or i >= k Or i >= m Or i >= n Or _
    j >= k Or j >= m Or j >= n Or k >= m Or _
    k >= n Or m >= n) _
    And (i + j + k + m + n) = SS Then
    Range("destination").Cells(p, 1) = i & ", " _
    & j & ", " & k & ", " & m & ", " & n
    p = p + 1
    End If
    Next n
    Next m
    Next k
    Next j
    Next i
    End Sub


  3. #3
    Michael R Middleton
    Guest

    Re: Find which numbers sum up to given total

    Keith Cunningham -

    > I have been presented with 13 numbers and given a total for the sum of 5
    > of these numbers. Will excel allow me to find which 5 of the given numbers
    > add up to my known total. <


    You could use Solver.

    The setup would be like the standard knapsack problem: thirteen binary
    variables as changing cells, each one indicating whether one of the thirteen
    numbers is included; a sumproduct of the binary variables times the numbers,
    as the target cell; a constraint that the sum of the binary variables equals
    five.

    - Mike Middleton
    www.mikemiddleton.com



  4. #4
    Ken Wright
    Guest

    Re: Find which numbers sum up to given total

    If you are looking for a solution (Not necessarily the only one) to a subset
    of a group of numbers that will add up to a target number, then this can be
    done quite simply with Solver.

    Assuming range of numbers in A1:A30, add a set of 0s in B1:B30 and in say
    B31 put

    =SUMPRODUCT(A1:A30*B1:B30)

    Now do Tools / Solver / Set Target Cell 'B31' to 'value of' and put in your
    target
    number. Then, using the range selector under the 'By Changing cells'
    section, select cells B1:B30 as the ones to change and hit enter which will
    take you back to the first dialog box. Now hit the 'Add' button, and add
    the constraint that B1:B30 must be 'bin' (Means binary as in 1 or 0, and
    it's one of the dropdowns, so just hit the arrow and select 'bin') and just
    hit Solve. You MUST ensure that in this example, when you add the 'bin'
    constraint range, you do not inadvertantly include the formula cell B31,
    else you will get an error message such as 'Binary Contsraint cell reference
    must include only adjustable cells'

    Won't do any more than single solution, but for a Finance Dept that will
    often
    suffice in this context.

    If you are going to look for more than one target number in the data, then
    with
    that formula in say B31, in B32 type the target number, and in B33 put
    =B32-B31.
    Now have Solver solve B33 = to 0 with the same constraints. Saves having to
    change any values in Solver that way, just type what you want in B32.

    Looks quite neat too if you format B1:B30 to a white Font and then use
    conditional formatting to highlight values in Col A where Val in Col B = 1

    --
    Regards
    Ken....................... Microsoft MVP - Excel
    Sys Spec - Win XP Pro / XL 97/00/02/03

    ----------------------------------------------------------------------------
    It's easier to beg forgiveness than ask permission :-)
    ----------------------------------------------------------------------------

    "Keith Cunningham" <keithcun@utvinternet.com> wrote in message
    news:3ao4qaF6b1hshU1@individual.net...
    > I have been presented with 13 numbers and given a total for the sum of
    > 5 of these numbers. Will excel allow me to find which 5 of the given
    > numbers add up to my known total.
    >
    >




  5. #5
    Herbert Seidenberg
    Guest

    Re: Find which numbers sum up to given total

    Even though binary is specified in B1:B30, Solver sometimes enters
    ..999999999999999 instead of 1.
    This makes the comparison of B32-B31 to zero fail.
    The comparison to 1 in conditional formatting will also fail.
    Also, since Keith wants 5 numbers, we have to add a constraint that
    the sum of B1:B30 is equal to 5.


  6. #6
    Ken Wright
    Guest

    Re: Find which numbers sum up to given total

    Agreed - Nothing is guaranteed but it's always worth a shot. You can always
    try using the ROUND function in there to reduce comparison errors, and
    that's something I'll always do for checksums and the like.

    --
    Regards
    Ken.......................


    "Herbert Seidenberg" <herbds7-msxls@yahoo.com> wrote in message
    news:1112126302.324152.63270@f14g2000cwb.googlegroups.com...
    > Even though binary is specified in B1:B30, Solver sometimes enters
    > .999999999999999 instead of 1.
    > This makes the comparison of B32-B31 to zero fail.
    > The comparison to 1 in conditional formatting will also fail.
    > Also, since Keith wants 5 numbers, we have to add a constraint that
    > the sum of B1:B30 is equal to 5.
    >




  7. #7
    Registered User
    Join Date
    12-29-2012
    Location
    Sydney, Australia
    MS-Off Ver
    Excel 2007
    Posts
    4

    Re: Find which numbers sum up to given total

    There is a cheap Excel Add-in called SumMatch that solves the problem "http://www.evolucion.com.au/Admin_Pages/SumMatch.aspx"


  8. #8
    Forum Moderator jeffreybrown's Avatar
    Join Date
    02-19-2009
    Location
    Cibolo, TX
    MS-Off Ver
    Excel 2007
    Posts
    8,067

    Re: Find which numbers sum up to given total

    Hi AlBear & Welcome to the Forum,

    I would think after 7+ years Keith Cunningham has got what he needs
    HTH
    Regards, Jeff

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