I do not think we can agree on that. I learned to do math in Roman numerals in grade school which is stupid simple and really beats it all into your head, for addition just pile all the numerals together brute force and reduce.

  XIV+XXIII = XXXVIIII = XXXIX

To multiply just break up one numeral and use the other to say how many . of each you have then add them.

  VI*VI = VI*V+VI*I = VVVVVVIIIIII = XXXVI

That is to say VI*VI is six Vs + six Is.

Subtraction is a little tricker since you need to convert numerals first but it is very simple to do in your head once you get it down and is easier to do in your head than on paper, same with multiplication and addition.

  XXII-IV = XVIIIIIII-IIII = XVIII

Division is not much fun with Roman Numerals unless you have an abacus which work quite naturally with the system and when doing addition, subtraction and multiplication in your head you quickly realize you subdivide and reduce the numerals in your head as you go in the exact same way and abacus works.

I bet you love both Roman's and their numeral system now. Next up, Vernier and his wonderfully accurate scale that lets your eyes see a difference of microns or even thousandths of an inch.