There is a continuing fascination with predecessor number systems like Roman Numerals. This Wikipedia site also discusses fractional notation and the subsequent use of the “zero” as N (standing for Null). There are sites which provide Arabic from/to Roman Numeral Converters and those that actually teach how to perform arithmetic operations using Roman numbers.
A little known function in Excel 2004 (maybe others) called roman(arabic_no,form) permits varying Roman Number succinctness. As the help facility notes: we have
0 for classic; 1, 2, 3 for more, more and more concise; and 4 for simplified. (Look up Excel Help for Roman form). In particular the number 499 has 5 (!) versions: CDXCIX, LDVLIV, XDIX, VDIV, and ID.
One of my favorite problems for Computer Programmers learning the C programming language (I taught this in the 1980s) was to write an Arabic to Roman Number Converter, using associative arrays of all the possible symbols as a preferred solution technique. It exercised many language aspects and involved arrays and pointers.
In this Sudoku variant, there is also no room for “small candidate” roman numbers, unless you use a classroom sized whiteboard. Reading clocks with Roman Numerals discloses that IV = IIII and that V, VI, VII and VIII are read while (they or you are) upside down. IV = IIII is done so that IV won’t be confused with an upside down VI, or so they say.