Converting Roman Numerals to Arabic Numbers

1
2
3
4
5
6
7
8
9
10
One
Two
Three
Four
Five
Six
Seven
Eight
Nine
Ten
I
II
III
IV
V
VI
VII
VIII
IX
X

 

11
12
13
14
15
16
17
18
19
20
Eleven
Twelve
Thirteen
Fourteen
Fifteen
Sixteen
Seventeen
Eighteen
Nineteen
Twenty
XI
XII
XIII
XIV
XV
XVI
XVII
XVIII
XIX
XX






Which number is equivalent to the Roman Numeral?