The unpaid balance at the start of a 30-day billing cycle was $676.81. No purchases were made during the billing cycle and a payment of $676.81 was credited to the account on day 21. Find the unpaid balance at the end of the billing cycle. Assume that the annual interest rate on a credit card is 20.95% and interest is calculated by the average daily balance method. The unpaid balance at the end of the billing cycle is $ (Round to the nearest cent as needed.)