From Chapter Four:

How Banks Charge You Interest, Penalties,
& Interest on Penalties
. . . Crushing Consumers with More Debt than They Bargained for
 
“It is well enough that people of the nation do not understand our banking and monetary system, for if they did, I believe there would be a revolution before tomorrow morning.”
 
—Henry Ford
Founder of Ford Motor Co.
& Innovator of Assembly-Line Manufacturing (1863–1947)
 
"Many consumer auto loans are formulated via the Rule of 78s. 7 Huh, I hear you say? First, I need to give you a couple of definitions. Principal is the amount of money you borrow in a given loan. If you take out a loan for $10,000, your principal balance is $10,000. Interest is the extra money you have to pay back to the bank on top of the principal they loaned to you. Interest is the bank’s profit in loaning you the money.
 
"Now, let me give you the definition of the Rule of 78s: The total number of months’ interest due in a 12-month year equals “78.” Simply put, on the 1st month of the loan, there are 12 months of interest due. On the 2nd month of the loan, there are 11 months of interest due. And so on and so forth up to month 12, when only 1 month of interest is due: 12 + 11 + 10 + 9 + 8 + 7 + 6 + 5 + 4 + 3 + 2 + 1 = “78.” That’s it! This explains why they call it what they call it. However, I still have to show you how the rule works, and more importantly, why it hurts you.
 
"The following article excerpts are taken, with thanks, from the website of Pine Grove Software, Princeton, New Jersey.8 My insertions are noted in parenthesis..."