What's that formula again? The one for when someone deposits periodically in an account/investing which generates a set value of imcome. For example, an account generates 10% a month, I open it up with 100 bucks and keep adding 100 more each month... Thanks.
do a search for "simple interest calculator" or "savings interest calculator". I think those are the ones you're looking for. edit: something like this? http://www.banksite.com/calc/savings