Answer
$6211$
Work Step by Step
$M=1000
\\D=500
\\C=100
\\L=50
\\X=10
\\V=5
\\I=1$
Note that:
(1) When a smaller number is written before a bigger number, the smaller number is subtracted to the bigger number.
(2) A bar on top means the value will be multiplied by $1000$.
Thus,
$\overline{V}MCCXI
\\= (5)(1000) + 1000 + 100+100+10+1
\\=5000+1211
\\=6211$
