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.

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.

ExcelTips is your source for cost-effective Microsoft Excel training. This tip (2424) applies to Microsoft Excel 97, 2000, 2002, and 2003. You can find a version of this tip for the ribbon interface of Excel (Excel 2007 and later) here: Summing Digits in a Value.