How can I do the SUM for my customer payments in ASP.

Ex: I have a customer who wants to pay his/her payment $100 per month...for

how many months he/she has to paid....we don't know yet... so I just do a

loop...it just loops....depends on his/her payments that he/she makes. The

question is how can caculate the total of it? Please give me some hints.

Thanks in advance.