What does MCCLI represent in roman numerals?

Answer 1

Add together the individual numerals (M = 1000, D = 500, C = 100, L = 50, X = 10, V = 5, I = 1) unless a smaller numeral precedes a larger one in which case subtract it from the larger one.

→ MCCLI = 1000 + 100 + 100 + 50 + 1 = 1251

Answer 2

M represents 1000, L is 50 and C is 100. This would convert to 1251.