find continuous data range

I received some help yesterday to find a continuous data range in Column A of a worksheet with a header in A1. But now I'm thinking that I asked the wrong question.

Each day I have new data (a series of numbers) that are moved into column A of a spreadsheet. I never know ahead of time how many numbers will be in the data set. And I need to perform a series of calculations on the data. I need to do the following:

1. Find the range of the data set.
2. Perform a series of calculations on the data set.
3. Report the results in a new location.

If #1 is pre-defined, then #2 and #3 are very easy. However, #1 is causing problems. I can find the range as a string (yesterday's help):

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and I can view the range of cells in a message box (e.g. A2:A101). But if I try to pass this information to a formula, I get an error.

Any help would be appreciated.

Thanks.

What's the formula?

VBA Noob

Thanks very much, Stephen. I was trying to do it this way (below), which does not work (following your "Sum" example):

Range("C1").Formula = "=Sum(r)"

However, your solution does work (below):

Range("C1") = WorksheetFunction.Sum(r)

To VBA Noob:
In this procedure, I'm calculating %RSD of a data set, as a measure of precision. The calculation applies to a log-transformed data set.

%RSD = 100 * (sqrt(K^((SD)^2)-1)
where K = 10^ln10

Thanks very much to both of you. Now I don't have to keep re-defining the data range each day, which has been painful.