Oh! My dear, it's amazing!

"...Today we are so used to writing numbers in decimal, that it is easy to forget that Gutenberg
would write the number 1448 as MCDXLVIII. How do you add two Roman numerals?
What is MCDXLVIII + DCCCXII? (And just try to think about multiplying them.) Even a
clever man like Gutenberg probably only knew how to add and subtract small numbers using
his ngers; for anything more complicated he had to consult an abacus specialist..."

I sign on the https://www.edx.org/ for course about "Theory of Quantum Information"!!
  
Quotation from here