It's because Romans mostly concerned themselves with counting things, and this is what the system was optimized for. When you want to add two roman numbers, yo

It's because Romans mostly concerned themselves with counting things, and this is what the system was optimized for. When you want to add two roman numbers, you just i. put them together, ii. sort the digits in descending order, and iii. shorten all "iiiii" to "v", all "vv" to "x", and so on. i. vii + xiii -> viixiii ii. viixiii -> xviiiii iii. xviiiii -> xvv -> xx