The Southern states wanted more representation in Congress. The number of Congressional Reps. that each state gets is based on the population totals of each state. Wyoming doesn't have very many people so they only get one Congressional Rep. California has a lot of people so they get 53 Congressional Reps.
The South wanted each slave to be counted in the census that takes place every 10 years to determine the population which determines the number of Reps. each state gets to have in Congress.
The North did not want the slaves to be counted in the census, therefore limiting the number of reps. that each southern state would have in Congress.
They came to a compromise. The 3/5th compromise. Every 5 slaves would be counted as 3 people in the census.
Somewhere along the line Black people were told by the Socialist Public School system that they were only considered to be worth 3/5th of a human and never explained anything beyond that. Based on that logic, if Libtards can be credited with ever actually using logic, it would have been the Northern States that would have considered the Slaves to not be human, and the Slave owners in the Southern states who wanted the Slaves to be considered human.