A $100,000 Mortgage at 7

Short Answer

A $100,000 mortgage at 7.3% compounded semi-annually with a 25-year amortization requires monthly payments. The mortgage allows the borrower to miss a payment once each year. How much will the amortization period be lengthened if the borrower misses the 12^th payment? (The interest that accrues during the 12^th month is converted to principal at the end of the 12^th month.)