VBA Mac coding Question

[LPUG]

Trying to write code to show prime numbers 3-1000, then show the sum of the digits of each of those prime numbers, and ultimately just show the prime numbers whose sum is prime. Example the number is 11 to show 1+1=2, 2 would also be shown because it is also a prime number. I have the code working for prime numbers, however cannot get it to sum the digits or show the summed primes. Please help!

[Aussiebear]

Have you tried this?

=SUMPRODUCT(--MID(A1,ROW(INDIRECT("1:" & LEN(A1))),1))

[Paul92688]

I see this was posted a few months ago. Are you still working on the problem? If so, you mention the sum of digits of 11 is 2 and 2 is prime. Are you summing all the digits of all the primes or only the sum of the digits that result in a prime sum? Are you doing this all in VBA or are you displaying all primes <1000 on a spreadsheet?

[Aussiebear]

Okay after a little homework...

This code will print Prime Numbers from 3 to 1000 in column A

Sub FindPrimesToColumnA()
  Dim i As Long
  Dim j As Long
  Dim IsPrime As Boolean
  Dim RowNum As Long
  RowNum = 1 ' Start writing primes from cell A1
  Cells(RowNum, 1).Value = 2 '2 is the first prime
  RowNum = RowNum + 1
  For i = 3 To 1000 Step 2
    IsPrime = True
    For j = 3 To Sqr(i) Step 2
      If i Mod j = 0 Then
        IsPrime = False
        Exit For
      End If
    Next j
    If IsPrime Then
      Cells(RowNum, 1).Value = i ' Write the prime number to column A
      RowNum = RowNum + 1
    End If
  Next i
End Sub

This next set of codes should produce the sum of umbers to make each Prime.

Sub PrimeSums()
  Dim i As Long, j As Long, k As Long
  Dim IsPrime As Boolean
  Dim RowNum As Long
  RowNum = 1
  Cells(RowNum, 1).Value = 2 '2 is the first prime
  RowNum = RowNum + 1
  For i = 3 To 1000 Step 2
    IsPrime = True
    For j = 3 To Sqr(i) Step 2
      If i Mod j = 0 Then
        IsPrime = False
        Exit For
      End If
    Next j
    If IsPrime Then
      Cells(RowNum, 1).Value = i 'Write prime number
      Cells(RowNum, 2).Value = FindSumCombinations(i) 'Write sum combinations
      RowNum = RowNum + 1
    End If
  Next i
End Sub


Function FindSumCombinations(target As Long) As String
  Dim a As Long, b As Long
  Dim result As String
  result = ""
  For a = 2 To target - 2 'Start from 2
    For b = a To target - a 'Start from a to avoid duplicates
      If a + b = target Then
        If result <> "" Then
          result = result & "; " 'Separate combinations with semicolon
        End If
        result = result & a & "+" & b
      End If
    Next b
  Next a
  FindSumCombinations = result
End Function