Roman numerals

Basic Principles

Big number followed by small number: ADD

Small number followed by bigger number: SUBTRACT small from big

Number followed by number of equal value: ADD

Small number with large number above: MULTIPLY

Examples:

  • I or j = 1
  • II or ij = 2 (1+1)
  • III or iij = 3 (1+1+1)
  • IIII or iiij or IV = 4 (1+1+1+1) or (5-1)
  • V =5
  • VI or vj =6
  • VII or vij = 7 (5+1+1)
  • VIII or viij = 8 (5+1+1+1)
  • IX or Viiij = 9 (10-1) or (5+1+1+1+1)
  • X = 10
  • XI or xj = 11 (10+1)
  • XIX = 19 (10+(10-1))
  • XX = 20 (10+10)
  • XXX = 30 (10+10+10)
  • XXXX or XL = 40 (10+10+10+10) or (50-10)
  • L = 50
  • LX = 60 (50+10)
  • LXX = 70 (50+10+10)
  • LXXX or iiijxx = 80 (50+10+10+10) or (4x20)
  • LXXXX or XC = 90 (50+10+10+10+10) or (100-10)
  • XCIX or iiijxxxix = 99 ((100-10)+(10-1)) or ((4x20)+10+(10-1))
  • C = 100
  • CI or cj = 101 (100+1)
  • CC = 200 (100+100)
  • CCC = 300 (100+100+100)
  • CCCC or iiijc = 400 (100+100+100+100) or (4x100)
  • D = 500
  • DC = 600 (500+100)
  • M = 1000
  • MDCCCCLXXXV or MCMLXXXV = 1985 (1000+500+100+100+100+100+50+10+10+10+5) or (1000+(1000-100)+50+10+10+10+5)

    But

  • Ml = 1000 (mille)
  • MM or MlMl = 2000 (1000+1000) (mille+mille)