Summing cells that have formula and string concatenated together - excel

Question

I have a column with formula as follows:
=(2+3*6+8) & "KB"
Basically, each cell is a formula and string concatenated (using &). I want to add all these cells up. I tried the following things:
a) =SUM(B2:B21) gives me a sum of 0.
b) Using =B2+B3... gives me a #VALUE error.
c) I tried something like this also - didn't work, gives a sum of 0: =SUM(IF(ISNUMBER(FIND("KB",$C$2:$C$14)),VALUE(LEFT($C$2:$C$14,FIND("KB",$C$2:$C$14)-1)),0))

Answer 1

Make your own SUM function in VBA. Try this:
=StripTextAndSum(A2:A4) - returns 60
=StripTextAndAverage(A2:A4) - returns 20
This method keeps the left most decimal number and tosses away the rest.
NOTE: You can tweak this to fit your needs. One way would be to retain the text so you can return it in the sum....like 150MB (i am assuming KB means kilobyte). Let me know if you like that idea and I'll make it.
EDIT: As pointed out by #DirkReichel, this has been made a little more efficient using IsNumeric instead, but I have retained all the other functions too. IsLetter is a useful function too.
Public Function StripTextAndSum(myRange As Range)
Dim r As Range
Dim n As Double
n = 0
For Each r In myRange.Cells
n = n + ParseNumberFromString(r.Text)
Next r
StripTextAndSum = n
End Function
Public Function StripTextAndAverage(myRange As Range)
Dim n As Double
n = StripTextAndSum(myRange)
StripTextAndAverage = n / (myRange.Cells.Count * 1#)
End Function
Public Function ParseNumberFromString(s As String) As Double
ParseNumberFromString = Left(s, GetLastNumberIndex(s))
End Function
Public Function GetFirstLetterIndex(s As String) As Integer
Dim i As Integer
For i = 1 To Len(s) Step 1
If IsLetter(Mid(s, i, 1)) = True Then
GetFirstLetterIndex = i
Exit Function
End If
Next i
End Function
Public Function GetLastNumberIndex(s As String) As Integer
Dim i As Integer
For i = Len(s) To 1 Step -1
If IsNumeric(Left(s, i)) = True Then
GetLastNumberIndex = i
Exit Function
End If
Next i
End Function
Function IsLetter(s As String) As Boolean
Dim i As Integer
For i = 1 To Len(s)
If LCase(Mid(s, i, 1)) <> UCase(Mid(s, i, 1)) = True Then
IsLetter = True
Else
IsLetter = False
Exit For
End If
Next
End Function

Answer 2

I'd normally just move the KB to the following column and left-justify it.
That way, it still looks identical but the first column only has real numbers that you can manipulate mathematically to your heart's content.
Or, assuming they're all in kilobytes (which seems to be a requirement if you just want to add the numeric bits), don't put KB in the data area at all.
Instead change the heading from, for example, Used memory to Used memory (KB).
Do you really want to populate your beautiful spreadsheets with butt-ugly monstrosities like the following? :-)
=SUM(IF(ISNUMBER(FIND("KB",$C$2:$C$14)),VALUE(LEFT($C$2:$C$1‌​4,FIND("KB",$C$2:$C$‌​14)-1)),0))

Answer 3

If you need to keep your column as-is, you could always use an array formula to get the sum:
=sum(value(left(b2:b21,len(b2:b21)-2)))
You will need to enter this as an array formula (press Ctrl+Shift+Enter to submit it)
Basically this is taking the leftmost chunk of a cell (all but the last two characters, which we know are 'KB'), using value() to convert it into a numeric, and sum() to add it up. Entering it as an array formula just lets us do this to each cell in the list b2:b21 in one swoop.
As #paxdiablo mentioned, though, it might be best to restructure so that you don't have to deal with your values as text in the first place. My approach would be to enter the values and add the "KB" via formatting. You can use a custom formatting with something like 0.00 "KB" so the cell only holds, say, the value 17, but it displays as "17.00 KB".