I don't think that is what the Constitution said. A slaveowner owning 100 slaves didn't get 61 votes. The actual wording is: "Representatives and direct Taxes shall be apportioned among the several States which may be included within this Union, according to their respective Numbers, which shall be determined by adding to the whole Number of free Persons, including those bound to Service for a Term of Years, and excluding Indians not taxed, three fifths of all other Persons." (article I section 2) What this meant was that a slave state would send more representatives to the House than it would have done if only the voting population were counted. (Of course, at the time, most states limited the franchise to people owning property of a certain value, and NO state allowed women to vote.)