Getting closer but not APR.
In order for the quiz to move on, I'll let this run for this evening and post a detailed answer tomorrow morning.
The ‘Rule of 78’ was a method of apportioning a fixed interest charge over the life of a loan. It was preferred by lenders in situations where there was a possibility of early repayment.
Thus on a 12 month loan, with monthly repayments, the agreed interest payment would be apportioned as 12 divided by 78 in the first month (with 78 being the sum of the digits one to twelve), 11 seventy-eighths in the second month, 10 seventy-eighths in the third and so on.
Clearly, this favoured the lender if the loan was repaid early, particularly in the early months. I believe money lenders favoured this method.
Somewhat surprisingly, in 1971 the method was endorsed by a government committee on consumer credit (Crowther). This led to some lenders receiving windfall gains on early repayments. Since 2005 a combination of tighter consumer credit regulations and ‘contract unfair terms’ legislation has effectively ended the use of the rule.
MotCO was getting close to the correct answer so I suggest he should be given the choice of asking a new question or declaring Open Floor.