Pretty common, there's a common joke at universities about how almost all historians are bad with maths and numbers (which I think there is something to).

Gets even worse when working on projects that spread between BCE and CE and you have to work with second century BCE and second century CE and having to work out how that works for both.

I mainly avoid using the terms when giving lectures and just stick to specific dates or say "around 200 BCE" etc. Much easier.

It is very counterintuitive. I have been writing and talking about history for 16 years, and sometimes catch myself out. Because of this, I never use terms like 18th century in our podcast, for exactly this reason.