900

900 is the largest number with multi-character undisputed which cannot be decomposed into two Roman numerals summing to itProof: 900 is expressed as CM, which can be only divided into C (100) and M (1000), which do not sum up to 900. For numerals larger than 900, all multi-character Roman numerals can be decomposed to two Roman numerals summing to it, as follows. Let the integer x. Let k=100 for x<1000 and k=1000 for 1000≤x≤3999. Then there are integers a and b with x = ak + b, 0<a<10 and 0≤b<k. Let the Roman numerals to x, ak, b as (x), (ak), (b). When b>0, (x) is expressed as concatenation of (ak) and (b), and decomposed to (ak) and (b) which sum up to x. When b=0, x=1000, 2000 or 3000, and they do not meet the criteria because
* 1000 is expressed as M and it is not multi-character.
* 2000 is expressed as MM and can be decomposed to M + M.
* 3000 is expressed as MMM and can be decomposed to M + MM. when we use the system of Roman numerals with characters IVXLCDM, which expresses up to 3999.Roman Numeral Converter accessed 2021-12-24
Nirvana Supermind calls this number zero-nonagenol, and is equal to Q<10,90> using quick array notation.Numbers from quick array notation - Integral View. Retrieved 2021-06-20.
== Footnotes ==
==Sources==
Category:Numbers
Category:Class 1
Category:Numbers with 3 digits
Category:Powers of 30
Category:Roman numeral-related numbers
Category:Unnamed numbers with ancient numerals