What does dccl mean 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 ones:

DCCL = 500 + 100 + 100 + 50 = 750