Il numero romano CCCXC nel sistema decimale vale: 390.
CCCXC in latino si scrive trecenti nonaginta,
mentre in italiano trecentonovanta.
CCCLXXI, CCCLXXII, CCCLXXIII, CCCLXXIV, CCCLXXV, CCCLXXVI, CCCLXXVII, CCCLXXVIII, CCCLXXIX, CCCLXXX, CCCLXXXI, CCCLXXXII, CCCLXXXIII, CCCLXXXIV, CCCLXXXV, CCCLXXXVI, CCCLXXXVII, CCCLXXXVIII, CCCLXXXIX, CCCXCI, CCCXCII, CCCXCIII, CCCXCIV, CCCXCV, CCCXCVI, CCCXCVII, CCCXCVIII, CCCXCIX, CD, CDI, CDII, CDIII, CDIV, CDV, CDVI, CDVII, CDVIII, CDIX