And could you tell me if there are any others?
assitant
I can show you an image of the numerals, like this:

XIIIIXVI

What’s confusing you? Is it that there’s two X’s?
assistant
Can you read Roman Numerals?
user
Yes, and I’m happy to help you with that, though I have to confess I don’t read Latin.  What are the Roman numerals for?
assistant
I saw them in a book. What is the number represented by XVI?
user