Using App Inventor to provide the amortization schedule and the sinking fund schedule

The present value of interest in the amortization schedule or the sinking fund schedule is derived in the theorem. Even though that people prefer the level payments with smaller total amount of interest, the sum of the present value of interest and the present value of principal remains unchanged in all payment methods. The sum is just the loan amount. Rather than the traditional spreadsheet, the free MIT App Inventor is applied to create the amortization schedule and the sinking fund schedule in the mobile computing environment.