<prompt> Human: Like the title states, Id like to make at least one additional mortgage payment each year to pay off my 30-year mortgage off sooner. Whats the best way to make this extra payment - save up and make an additional payment all at once or add in an extra 100 to each monthly payment?  <response>: the amount of interest you are charged each month is determined by the following formula:your interest rate divided by 12 multiplied by your remaining principleso the earlier you pay down the principle, the more interest you save. 