The short answer is try using the =FORECAST() function, where the known_y's
are your values, the known_x's can just be 1, 2, .. 10 (or =MONTH() of the
date) and then the points for which you want to predict a value are 11 and 12.
However, this makes a huge assumption that the relationship is linear. So
the first step has to be simply to plot them and see if this assumption is
valid. If it is, FORECAST is perfectly OK. If they are something that is
growing at a constant rate then =LOGEST() might be the function to use.
Otherwise you're moving into much more complex area.
HTH, David Jessop
