[header] How to use roman numerals [title] Understand the concept of roman numerals. [step] Roman numerals use fewer symbols than the number system you are used to. I is the number 1 (one), v is 5 (five), and x is 10 (ten), for example. 
Counting starts out as easy as i (one), ii (two), iii (three). But for the next one, write iv for " one away from five " (i away from v), which is four.