I recall seeing IIII in my Cicero class and expressing confusion, but being informed by the professor that said style was more common historically.
The Wikipedia citation for 9 is Commentarii de bello Gallico (Julius Caesar's Commentaries on the Gallic War), which interestingly comes from around the same timeframe (first century BC, toward the end of the Roman Republic).
The Wikipedia citation for 9 is Commentarii de bello Gallico (Julius Caesar's Commentaries on the Gallic War), which interestingly comes from around the same timeframe (first century BC, toward the end of the Roman Republic).