Variants are 16 bytes. I ran it with all variants, only converting to Decimal when placing the results on the sheet and without even that conversion and saws no difference.

After converting all numeric variable to Variants and using these calculations the results were identical to the 10th digit with the other methods. Note that I kept the Magic number 100. It made a difference when I subtituted the Variant C = CDec(100) for the Magic number

''''Calcuate results for one file
      For CR = 0 To UBound(FileLines)
         'Replace file line with Log of 6th value. Split(BlahBlah)(5)
        F_Array(CR) = CDec(Log(Split(FileLines(CR), ",")(F)) / Log(10#)) '<<<<<<<<<<
         'After the first line
        If CR > 0 Then
          Sum_L = Sum_L + ((F_Array(CR) - F_Array(CR - 1)) * 100) ^ 2
          Q_Array(CR) = Abs((F_Array(CR) - F_Array(CR - 1)) * 100)
          Sum_Q = Sum_Q + (Q_Array(CR) * Q_Array(CR - 1))
        End If
      Next CR
I believe that the VBA method is that much more precise than the Excel On-Sheet method, which is limited to 15 significant places.

I need to go back and edit my "Accuracy" post above.

With 100 to 150 lines, Excel is accurate to +-3 in the third
With With Double Type numerical variables, VBA is accurate to 11 places
Assuming that using all decimals is the most precise.

1st Formula Results
table_abbv.csv table_abt.csv table_aapl.csv
Number of lines 94 106 151
Excel 2.5820251543270400 1.2249023888699800 0.5047631412720350
Doubles 2.5820251543270400 1.2249023888699900 0.5047631412719940
Decimal Variables 2.5820251543248600 1.2249023888700300 0.5047631412714680
2nd Formula Results
Excel 1.7327113499938000 0.8586603953426530 0.4404276525780680
Doubles 1.7327113499937800 0.8597056301514100 0.4422153315780190
Decimal Variables 1.7327113499905900 0.8597056301520180 0.4422153315780510