It's the same as why you wouldn't measure your weight in ounces, but neither would you weigh something very light in pounds - you want a convenient number which is easy to interpret. PC is short for parsec and it's a unit of measurement equal to 3,000,000,000,000,000,000 cm!
Take your annual covered earnings (the earnings on which you pay Social Security payroll taxes), multiply it by that year's index factor and you will obtain your indexed wage for each year you have worked. Next, add up all these indexed wages and divide them by 35 to determine your average wage.
1 You can earn wages up to the earnings limit of $14,640 with no reduced Social Security. 2  In 2012, any money you make over the earnings limit of $14,640 will reduce your Social Security payments.3  Every $2 you make over the limit reduces your Social Security payments by $1. 4  For 2013, that limit is $15,120. You can earn wages up to the earnings limit of $14,640 with no reduced Social Security. 2  In 2012, any money you make over the earnings limit of $14,640 will reduce your Social Security payments.