Il numero romano MDCCCXX nel sistema decimale vale: 1820.
MDCCCXX in latino si scrive mille octingenti viginti,
mentre in italiano milleottocentoventi.
MDCCCI, MDCCCII, MDCCCIII, MDCCCIV, MDCCCV, MDCCCVI, MDCCCVII, MDCCCVIII, MDCCCIX, MDCCCX, MDCCCXI, MDCCCXII, MDCCCXIII, MDCCCXIV, MDCCCXV, MDCCCXVI, MDCCCXVII, MDCCCXVIII, MDCCCXIX, MDCCCXXI, MDCCCXXII, MDCCCXXIII, MDCCCXXIV, MDCCCXXV, MDCCCXXVI, MDCCCXXVII, MDCCCXXVIII, MDCCCXXIX, MDCCCXXX, MDCCCXXXI, MDCCCXXXII, MDCCCXXXIII, MDCCCXXXIV, MDCCCXXXV, MDCCCXXXVI, MDCCCXXXVII, MDCCCXXXVIII, MDCCCXXXIX