Plot the data. See if a linear fit is "good enough". Then try some sample
fits:

http://spreadsheetpage.com/index.php...line_formulas/
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Gary''s Student - gsnu201001


"Jul2010" wrote:

I have some monthly historical sales data and would need to do a forecast for
next 12 month.
Question - sales number - how can identify the closest rule on their growth
or change? Is there a way to accurately identify the growth type - linear or
exponential or any any other?