Good Day to you all!!! Very quiet here, I see. Hopefully, we are all studying about mortgages and interest!! HA!!!!!!! Where the hell is strat??? OK, my "final" words on this subject;
This is not a matter of "simple" interest. This is about amortized mortgage interest. An amortization table will show you how direct-reduction works. When you initially take a mortgage loan, your monthly payment is mostly interest and a little principal. In the first seven years or so, you pay only about 10% of the original balance. The rest is interest payment. It takes roughly 20 years to pay about HALF your balance! Of course, the amount of the principal paid does increase year after year and, in the last five years or so, you get a reversal and are paying mostly principal and little interest.
Keep in mind that, no matter how small the interest payment, you still are paying at the same interest rate. 6% is always 6% throughout the life of your loan. The interest you are paying is on the amount that is outstanding in any given year. The dollar amount of interest you pay goes down because the balance (principal) goes down. The interest rate is still constant.
There are ways to get around the dollar amount paid. It is known as acceleration. Most people do this by paying a half-payment every two weeks instead of once a month. (Bi Weekly) this reduces the dollar amount of interest you pay IF you have a loan that allows it. THERE is ANOTHER story!! Pre-payment penalties! Usually, you are not allowed to pay more than 20% of the outstanding balance in any given year because banks WANT that interest dollar!
There is more but I think I have made my point. I have done this for TWENTY freakin years. It is not a simple formula. MOST people do not understand it and they pay far more than they have to as a result. Class dismissed.