7 of them and they are: M=1000, D=500, C=100, L=50, X=10, V=5 and I=1
In todays modern notation of Roman numerals they represent: 1990
In today's notation they represent 390
The Roman numeral XC represents the number 90
16
LV
D
V
That is 29.
MCXVII
10 = X in Roman numerals
3409 in Roman numerals is MMMCDIX
DCCCXXXII in roman numeral is 832.