How many days of slave labor were there cumulatively in the U.S.?

by AbsentThatDay

If a country had 10 slaves, for 10 days, we could say there were 100 days of slave labor. What would the result be for the U.S. during the course of legal slavery?

AbsentThatDay

If anyone has a suggestion about how I might better word this question, or a better place to post it, I'm all ears.