Author: Oscar Cronquist Article last updated on April 30, 2019

This article describes how to find a sum from a range of numbers using a user defined function.

Let´s see how quickly excel solver finds the numbers using the instructions from this post: Identify numbers in sum using solver in excel.

The sum is 1832,3 and it takes around 15 seconds to find the numbers.

With my beginner vba skills I created an user defined function to find numbers in a sum. See picture below.

The udf finds two sets of numbers in a second.

UDF in A23:Q25:

=Find_num(A1:A17, B20)

To enter an array formula, type the formula in a cell then press and hold CTRL + SHIFT simultaneously, now press Enter once. Release all keys.

The formula bar now shows the formula with a beginning and ending curly bracket telling you that you entered the formula successfully. Don't enter the curly brackets yourself.

Formula in R23 sums the numbers. Here is another example:

User defined function:

Function Find_num(rng As Range, cell As Range)

Dim com() As Single, c As Single, i As Single
Dim s As Single, d As Single, u As Single, v As Single
Dim arr() As String, r As Single, p As Single, t As Single
Dim sum_cells As Single, j As Single, k As Single, l As Single

sum_cells = Application.WorksheetFunction.Sum(rng)
c = rng.Rows.Count
ReDim arr(1 To 1000, 1 To c)
r = 1

For i = 0 To Int(c / 2)
  If i <> Int(c / 2) - 1 Then
    t = WorksheetFunction.Combin(c, i + 1)
    t = WorksheetFunction.Combin(c, i + 1) / 2
  End If
  ReDim com(i)
  For j = 0 To i
    com(j) = j + 1
  k = i
  For s = 1 To t
    If com(k) > c And i > 0 Then
      p = 0
      Do Until com(k) <= c - p 
        com(k - 1) = com(k - 1) + 1 
        k = k - 1 
        p = p + 1 

      Do Until k >= i
        k = k + 1
        com(k) = com(k - 1) + 1
    End If
    d = 0
    For j = 0 To i
      d = d + rng(com(j))
    Next j
    If d = cell Then
      For j = 1 To i + 1
        arr(r, j) = rng(com(j - 1))
      Next j
      r = r + 1
    End If
    If sum_cells - d = cell Then
      For j = 1 To c
        v = 0
        For u = 0 To i
          If rng(com(u)) = rng(j) Then v = 1
        Next u
        If v = 0 Then
           arr(r, j) = rng(j)
        End If
      Next j
      r = r + 1
    End If
    com(k) = com(k) + 1
  Next s
Next i

Find_num = arr()

End Function


How to add the User defined Function to your workbook

  1. Press Alt-F11 to open visual basic editor
  2. Click Module on the Insert menu
  3. Copy code above
  4. Paste code to code module
  5. Exit visual basic editor and return to excel
Note: Save your workbook with file extension *.xlsm to keep the code in your workbook.

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