What is the roman numeral for the number 0?

Answer 1

The Romans had no numeral for zero. Zero as a concept was invented later.

The equivalent Roman symbol for zero is N and was rarely used because the positional place value of Roman numerals are self evident.

As the ancient Romans used them Roman Numerals had NOpositional values at all; they would have read both VI and IV as 6 and VIIII, IIIIV, IVIII, IIVII, and IIIVI as 9. The numerals were only usually written from largest to smallest by traditionand the fact that they were being transcribed from an abacus in that order. The concept of relative positional values in modern Roman Numerals was only invented in the middle ages by lazy christian scribes working in monasteries. The only case where anyone ever used N to represent zero in Roman Numerals was to represent the whole number zero in the rare cases when it was a calculated answer, never as a digit or positional place holder within another number.