In Roman numerals, we can repeat I (value of 1) or any letter (except L and D) only 3 times.
e.g. VIII, XIII, XVIII, VI, VII, XI, XII, XXX
Incorrect: VIIII, XVIIII, XXIIII, XXXX
In Roman numerals, when the letter which have higher value comes first than the second letter, we add.
e.g. VI, XI, MI, DI, DII
In Roman numberals, when the letter which have lower value than the second letter, we subtract.
e.g. IV, IX, IM, ID
Now, here is the REAL equation of Vicarivs Filii Dei:
Note: All the letters in blue means they have no value in Roman numerals.
