The most usual way (these days) is IV.
However the romans often used IIII and you will still see IIII on clocks that use roman numerals.
Roman numerals do not make provision for decimals. 22 is XXII
8D Nonono, Roman Numerals were a counting system. Just like you can't make letters with 123..., you can't make letters for numerals.
DLXXIV
1109
DCCCXXXII
MMXIII
VI
CCCXIX
II
476 = CDLXXVI in Roman numerals
We still use Roman numbers today. One place where you often see Roman numbers is on a clock face. We generally make use of less of Roman Numerals.3604262 in roman numerals is MMMDCMMMMCCLXII.
Roman numerals were inspired by Etruscan numerals of which Roman numerals originated from.