how do you create a sub-total in numbers for each category
I'm new to Numbers and would like to add up columns into sub-totals for each category. I've fumbled about a bit with help and formulas, but cannot easily find how to add in the necessary row or formula at the end of each category. The template gives me one total line at the end, which I can manage, but how do I separate out the sub-total formulas for each sub-category and then direct it to add the sub-totals into the final total (without double-counting the sub-total on top of the individual amounts)? Thank you for your help.
iMac, Mac OS X (10.7.1)