4 of 4 dropped unnecessary parens (-1 char)

Ruby, 134

i=gets
%w[IV,4 IX,9 XL,40 XC,90 CD,400 CM,900 I,1 V,5 X,10 L,50
C,100 D,500 M,1000].map{|s|k,v=s.split ?,;i.gsub!(k,?++v)}
puts eval i