Big Roman Numbers

The Romans only had symbols for numbers up to a thousand, so how did they cope with really big numbers- a million for instance? Surely they didn't write MMMMMMMMMMMMMMMMMMMMMMMMMMMMMMM......?  This was keeping me awake last night. 

I looked up the answer this morning. You put a bar across the top of a number and that shows you've multiplied it by a thousand. So a million is M with a bar across the top.  

Like so....



Simplicity itself!