Suppose that you take out a federal direct loan on September 1 before your senior year for $6600 and plan to begin paying it back on December 1 after graduation (so you will have had the loan for 15 months, including the six-month grace period after leaving school). The interest rate is 4.29% and you pay the interest every quarter until that December 1. How much will you owe on that December 1, and how much of that will be interest?

The answer is NOT 6961.59 or 6961.60