If the roman numeral system does not have a zero symbol then what does X minus X leave in terms of numerical notation?

Answer 1

-12 -11 -10 -9 -8 -7 -6 -5 -4 -3 -2 -1 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19

Consider the expression: -10+10. This expression is actually instructing you to move 10 places forward from -10 on the above number line which brings you onto zero.

Likewise, the expression: -X+X is instructing you to do exactly the same thing which also brings you onto zero or nihil as the Romans would say.

Now consider the numerals IX, they are instructing you to move 10 places forward from -1 which brings you onto 9.

Then consider the numerals VIIII, they are instructing you to move 9 places forward from 0 which naturally brings you onto 9.

It is for the above reasons why 19 in Roman numerals is IXX or XVIIII and not XIX.

Therefore the Roman numeral system did and does have a representation for zero, probably a symbol such as N. Indeed, it would be impossible to add up without it!

David Gambell, Merseyside, England.

Alternative answer The Romans did not have a numeral for zero as they did not use it. In the 8th century monks who used Roman numerals introduced the symbol N (as an abbreviation of the Latin word nullae) to symbolise zero. Roman numerals read from left to right, starting with the highest value number. Clearly XIX (10 + 9) which starts with a ten follows this rule and so does XVIIII (10 + 5 + 4) but IXX (9 less than 10 or 1 less than 20) which starts with I, the symbol for 1, does not.