Sum (κεφαλαίου)

Lit., capital. The purchase of Roman citizenship was an investment. Under the first Roman emperors it was obtained only at large cost and with great difficulty; later, it was sold for a trifle.

I was free-born (ἐγὼ καὶ γεγέννημαι)

Lit., I am even so born, leaving the mind to supply free or a Roman. Better, as Rev., I am a Roman born.

Acts 22:28 Parallel Commentaries

But. It is extremely probable that the inhabitants of Tarsus, born in that city, had the same rights and privileges as Roman citizens, in consequence of a grant or charter from Julius Caesar, from whom it was called Juliopolis. But if this were not the case, Paul's father, or some of his ancestors, might have been rewarded with the freedom of the city of Rome, for his fidelity and bravery in some military service, as Josephus says several of the Jews were; or his father might have obtained it by purchase, as in the instance of the chief captain.