Summing Digits in a Value

If you have a cell that contains a value, you may want to devise a way to add together all the digits in the value. For instance, if a cell contains the value 554, you might want to determine the sum of 5+5+4, which is 14.

There are several ways you can approach this task. (Doesn't that always seem the way in Excel?) The first is to use a formula that relies on several functions:

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

This regular formula will sum the digits in any integer value (in cell A1) in a simple, elegant manner. This is not the only possible formula, however. The following is an array formula (terminated by pressing Ctrl+Shift+Enter) version of the same formula:

=SUM(1*MID(A1,ROW(INDIRECT("1:"&LEN(A1))),1))

Either of these formulas work fine if the value in A1 is a positive whole number. If there are any non-digit characters in the number (such as a negative sign or a decimal point), then the formulas return a #VALUE! error.

These are not the only formulas possible for this type of calculation. You can find some other examples of formulas in the Microsoft Knowledge Base:

http://support.microsoft.com/?kbid=214053

You can also use a user-defined function to return the desired sum. The following macro steps through each digit in the referenced cell and calculates a total. This value is then returned to the user:

Function AddDigits(Number As Long) As Integer
    Dim i As Integer
    Dim Sum As Integer
    Dim sNumber As String

    sNumber = CStr(Number)
    For i = 1 To Len(sNumber)
        Sum = Sum + Mid(sNumber, i, 1)
    Next
    AddDigits = Sum
End Function

To use this function, just use a formula such as =AddDigits(A1) in a cell. An even more compact user-defined function (invoked in the same manner) is the following:

Function AddDigits(ByVal N As Long) As Integer
    Do While N >= 1
        AddDigits = AddDigits + N Mod 10
        N = Int(N / 10)
    Loop
End Function

Unlike the earlier macro, this version doesn't convert the cell contents to a string in order to process it. Instead, it steps through each digit of the value, stripping off the last digit and adding it to the total.