Roman <codec>
from 1…18,446,744,073,709,551,615
Encoding successful The roman numeral equivalent of `999,999,999,999,999,999` is `C̅̅̅̅̅M̅̅̅̅̅X̅̅̅̅̅C̅̅̅̅̅I̅̅̅̅̅X̅̅̅̅̅C̅̅̅̅M̅̅̅̅X̅̅̅̅C̅̅̅̅I̅̅̅̅X̅̅̅̅C̅̅̅M̅̅̅X̅̅̅C̅̅̅I̅̅̅X̅̅̅C̅̅M̅̅X̅̅C̅̅I̅̅X̅̅C̅M̅X̅C̅I̅X̅CMXCIX`.
What is the bar above the numeral? The large numeral contains a
vinculum. Each bar represents the numeral multiplied by 1,000. If you do not see a line above the numeral, then your browser's monospace font does not support this diacritical mark.
Here are some others for you to try...