What is the largest number that can be represented by Roman Numerals?

Answer 1

M with a bar over it for one million
For very large numbers (five million and above), there is no standard format, although sometimes a double bar or underline is used to indicate multiplication by 1,000,000. That means an underline X is ten million.

Answer 2

Each year they are finding new ways to use Roman Numerals in order to keep up with the superbowl. I suppose when football is over so is the Roman Empire.

Answer 3

Ironicaly, it is exactly the same as the largest number that can be represented by Arabic numbers.