Curious as to how the average Roman did simple math using Roman
Numerals. There doesn't seem to be any way to add MCVII plus MMDXIV
without converting to numbers. Simple addition subtraction division
and multiplication seems impossible using Roman numerals. So how did
the average Roman businessman do his accounting?

This may help:

http://en.wikipedia.org/wiki/Roman_arithmetic

Also, it is important to remember that this was their number system,
when they saw  XVI they thought "(roman word for) 16"  They may have
had trouble teaching "shortcuts" but for the most part I think they
probably did mental math, I honestly can't remember the last time I
had to carry a 1 on a piece of paper, or do "long division".  This
also could be the reason why most Romans weren't math scholars.

If I read the info correctly at the link provided above, Romans didn't
do math in Roman Numerals. Calculations seemed to have been done on a
counting board with the resulting answer than turned into a numeral. I
imagine some one who knew how to use a counting board must have been a
highly paid employee in Roman times. Reminds me of the individuals who
used to calculate train schedules before the onset of railroad time.