Il numero romano CCLXXX nel sistema decimale vale: 280.
CCLXXX in latino si scrive ducenti octoginta,
mentre in italiano duecentottanta.
CCLXI, CCLXII, CCLXIII, CCLXIV, CCLXV, CCLXVI, CCLXVII, CCLXVIII, CCLXIX, CCLXX, CCLXXI, CCLXXII, CCLXXIII, CCLXXIV, CCLXXV, CCLXXVI, CCLXXVII, CCLXXVIII, CCLXXIX, CCLXXXI, CCLXXXII, CCLXXXIII, CCLXXXIV, CCLXXXV, CCLXXXVI, CCLXXXVII, CCLXXXVIII, CCLXXXIX, CCXC, CCXCI, CCXCII, CCXCIII, CCXCIV, CCXCV, CCXCVI, CCXCVII, CCXCVIII, CCXCIX