Discusses the mathematics involved in comparing the purchase of an automobile with cash versus with a loan. Investigates two scenarios: (1) if a loan is taken out and the cash price is invested at a fixed rate, and (2) if cash is paid and monthly payments are invested over the period of the loan. (MDH)

Presents two teaching ideas. The first helps students identify and correct their own mistakes. A checklist of common mistakes is filled out by students after quizzes and tests and examined for error patterns. The second develops the formula to determine the payments necessary to pay off a loan over a required period of time. (MDH)

Discusses the use of technology in solving compound interest-rate problems that can be modeled by linear relationships. Uses a graphing calculator to solve the specific problem of determining the amount of money that can be borrowed to buy a car for a given monthly payment and interest rate. (MDH)