It is: CD = 500-100 = 400
If you mean CD plus DC then in Roman numerals they add up to M meaning 400 plus 600 = 1000
CD = 400
XL=400 * * * * * No. XL is the Roman number 40. 400 is CD.
400
CD
400 = CD
CD
It's already in numeric order but if you mean in Roman numerals then it's CD
CD = -100+500 = 400
CD-D
1465 as M=1000 CD=400 LX=60 V=5