Two ways to do it fairly easily
have a data set without your forecast. Plot it , set line and symbol to
none select the legend line it is on and clear all. set the trendline on
this set.

calculate the best fit equation for the data you wish to use and plot this
line as a separate series.

"Mary Ann" wrote:

Me again with more charting questions!

I have a column chart showing 6 months actual sales for a product followed
by the next two months forecast figures.

I want to show a trendline based only on the 6 months actual sales i.e. the
trend should not take into account our forecast. The trendline I normally
use is a linear trend.

Is there a way to do this?