I have a formula in a range of cells in a worksheet which evaluate to numerical values. How do I get the numerical values in VBA from a range passed into a function?

Let's say the first 10 rows of column A in a worksheet contain rand() and I am passing that as an argument to my function...

public Function X(data as Range) as double

    for c in data.Cells
        c.Value    'This is always Empty
        c.Value2   'This is always Empty
        c.Formula  'This contains RAND()
    next

end Function

I call the function from a cell...

=X(a1:a10)

How do I get at the cell value, e.g. 0.62933645?

Excel 2003, VB6