1 in Roman numerals, how to write?

1 = I
0 = ? ... 2 = ?

In Roman numerals online converter

Latest conversions of numbers to Roman numerals

1 = I Jan 21 22:33 UTC (GMT)
1,990 = MCMXC Jan 21 22:33 UTC (GMT)
6 = VI Jan 21 22:33 UTC (GMT)
28 = XXVIII Jan 21 22:33 UTC (GMT)
2,017 = MMXVII Jan 21 22:33 UTC (GMT)
31 = XXXI Jan 21 22:33 UTC (GMT)
5 = V Jan 21 22:33 UTC (GMT)
28,000 = (X)(X)(V)MMM Jan 21 22:33 UTC (GMT)
1,846 = MDCCCXLVI Jan 21 22:33 UTC (GMT)
3,998,884 = (M)(M)(M)(C)(M)(X)(C)(V)MMMDCCCLXXXIV Jan 21 22:33 UTC (GMT)
99 = XCIX Jan 21 22:33 UTC (GMT)
21 = XXI Jan 21 22:33 UTC (GMT)
9 = IX Jan 21 22:33 UTC (GMT)
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