Well, this is a broad question, so I'm not quite sure what answer you're looking for, but the simplest answer, which used to get me confused, is: the monomer is a repeat unit of the polymer. Let's start by analyzing the words monomer and polymer. Mono = one, and poly = many. Now, lets go back to the science.
History of the United States with 150+ answers. According to one source: Twelve American presidents owned slaves, eight while serving in office, and at least 25 presidents count slave owners among their ancestors.. http://www.slate.com/articles/li... However, to put this into perspective this would be 37 that were either slave owners themselves or descended from slave owner ancestors - or 84%.
George Washington, the first President of the United States, held people in slavery for virtually all of his life. His will provided for freeing the enslaved people he held upon the death of his widow Martha Washington. In January 1801 Martha freed her husband's slaves, just over a year after his death.