[ent]

Actually, roman numerals are easier to sum than arabics. To sum two roman numerals you just write all the digits together and collapse them as much as possible. There is no carrying over of digits and such.

Otoh, arabic numerals are a lot easier to multiply/divide. Before the wide adoption of arabic numerals all but the most educated couldn't perform simple multiplication/division.

[paradoja]

You may have a point, but I still find easier to do

         111
 948      948
 289  =>  289
 ---      ---
         1237

than

CMXLVIII plus CCLXXXIX => CMCCXLLXXXIXVIII => MCLLXXIXVIII => MCCXXXVII

but it may be that it's because what I'm used to.