OK, class. You’ve been reading my column for a number of years now. It’s time to see how much you’ve learned. So put on your thinking caps, get out your No. 2 pencils, and good luck with this short pop quiz. Question 1: How many years of earnings are used to compute a Social Security retirement benefit? And are your actual earnings used, or a variation of those earnings? Question 2: If you are 62 and working full time, can you sign up for reduced Social Security benefits? Question 3: What is the bonus that you get if you delay benefits beyond your full retirement age? Question 4: You can take reduced benefits at age 62 on your spouse’s record and later switch to full benefits on your own Social Security record: true or false? Question 5: Husband Hank’s full retirement age benefit is $2,000 per month. But he delayed benefits …