What are the roman numerals?

if you want 4 and V is 5 since 4 is a lower number you put an I befor the V there for it subtraks 1 from V which is 5 and if you put it on the other side like so VI it adds 1 so now its 6 thats haw it works if you want it to be one lower than a mane number you put an I before it and 1 hier you puty it after sorry for speling errors