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%.
Based on his well-documented research, he says 12 of our presidents owned slaves and eight of them owned slaves while serving as president. Zachary Taylor was the last sitting president to own slaves. Taylor owned 100 slaves and a Mississippi plantation, but he also opposed the extension of slavery to new territories. In 1850 the former Army general told a group of angry Southerners that if they seceded he would personally lead the Army and hang anyone taken in rebellion against the Union.