[memling]

> Can anyone explain this?

Slave names were sometimes numbers. Naming conventions in Roman culture were apparently also fairly formal.[0] I would guess there's sufficient evidence here that a ratio of free to slave could be estimated.

In general, it seems like being a slave was not a great experience.[1]

[0]: https://en.wikipedia.org/wiki/Slavery_in_ancient_Rome#Treatm...

[1]: among other stories, the one concerning the murder of Lucius Pedanius Secundus sticks in my mind: https://en.wikipedia.org/wiki/Lucius_Pedanius_Secundus

[sedatk]

> it seems like being a slave was not a great experience

It was definitely frowned upon.

[brazzy]

> Slave names were sometimes numbers.

Senators' and emperors' names were quite often numbers.

That is definitely not the distinction you're looking for.

[dumdumchan]

"Janus the fifth" and "KD6-3.7"

[brazzy]

That's not at all how it worked.

"The fifth slave I bought" and "the fifth son of this super rich senator" would have exactly the same name, Quintus.

[Pigalowda]

Cicero’s less famous brother was named Quintus.

Pompey Magnus had a son, Sextus (6th), that was relatively famous for his opposition to Octavius.

[memling]

Not sure precisely why you're being downvoted for bringing some additional light to the conversation. Been busy here but appreciate the insights; this isn't my field. Are there good sources that clarify the complexities of Roman naming conventions?

[mcpackieh]

> "Janus the fifth"

You're thinking along the lines of generational suffixes? There were Roman emperors who's family name (nomen gentilicium) was a number, the same number being used by son, father, grandfather... not incrementing with each generation.

There were also Roman emperors who's fathers had been slaves.

Lucius Septimius Severus - family name means 7th

Publius Helvius Pertinax - family name means honey-yellow. Son of a freed slave.