I created an ammoritization schedule for mortgage loans.

I have the following columns:

A B C D
E F
Month Principal Balance Payment Interest
Principal Outstanding Balance


There are 360 months (and thus, 360 rows below the above row) and I SUM
columns C, D, E, respectively.
The problem is, if I create a table of only 240 months or 200 months, it
will insert ( ) for everything past this new month (i.e., I zero out at 240
mos, but the table continues on to 360, adding all the negative numbers for
241-360), and give me a skewed total. How can I get it to only SUM the
positive numbers, or better yet, don't display anything past the chosen
term?

Thank-you, and please let me know if any other information is needed.

Jacob