Il numero romano MMMMCXXIII nel sistema decimale vale: 4123.
MMMMCXXIII in latino si scrive quattuor milia centum viginti tres,
mentre in italiano quattromilacentoventitré.
MMMMCIV, MMMMCV, MMMMCVI, MMMMCVII, MMMMCVIII, MMMMCIX, MMMMCX, MMMMCXI, MMMMCXII, MMMMCXIII, MMMMCXIV, MMMMCXV, MMMMCXVI, MMMMCXVII, MMMMCXVIII, MMMMCXIX, MMMMCXX, MMMMCXXI, MMMMCXXII, MMMMCXXIV, MMMMCXXV, MMMMCXXVI, MMMMCXXVII, MMMMCXXVIII, MMMMCXXIX, MMMMCXXX, MMMMCXXXI, MMMMCXXXII, MMMMCXXXIII, MMMMCXXXIV, MMMMCXXXV, MMMMCXXXVI, MMMMCXXXVII, MMMMCXXXVIII, MMMMCXXXIX, MMMMCXL, MMMMCXLI, MMMMCXLII