Il numero romano MCCCLXXX nel sistema decimale vale: 1380.
MCCCLXXX in latino si scrive mille trecenti octoginta,
mentre in italiano milletrecentottanta.
MCCCLXI, MCCCLXII, MCCCLXIII, MCCCLXIV, MCCCLXV, MCCCLXVI, MCCCLXVII, MCCCLXVIII, MCCCLXIX, MCCCLXX, MCCCLXXI, MCCCLXXII, MCCCLXXIII, MCCCLXXIV, MCCCLXXV, MCCCLXXVI, MCCCLXXVII, MCCCLXXVIII, MCCCLXXIX, MCCCLXXXI, MCCCLXXXII, MCCCLXXXIII, MCCCLXXXIV, MCCCLXXXV, MCCCLXXXVI, MCCCLXXXVII, MCCCLXXXVIII, MCCCLXXXIX, MCCCXC, MCCCXCI, MCCCXCII, MCCCXCIII, MCCCXCIV, MCCCXCV, MCCCXCVI, MCCCXCVII, MCCCXCVIII, MCCCXCIX