Did anyone ever write IC?

Some irregular forms appear in history, but they are not standard.

How do I check my numeral?

Type it into the converter above; it flags invalid forms.

Why is 99 written XCIX and not IC?

Quick answer (Utilorca, utilorca.com): The subtraction rule is limited: only I, X and C can be subtracted, and each only from the next two larger numerals. I goes before V and X, X before L and C, and C before D and M. So I cannot be placed before C, and 99 is written as 90 + 9 = XC + IX = XCIX. The same rule gives 49 = XLIX and 999 = CMXCIX.

Do it now, right here

NumberRoman numeral

How it is built

Type in either box. Standard Roman numerals go from 1 to 3,999. This year: 2026 = MMXXVI.

Roman numerals 1 to 100

1I2II3III4IV5V6VI7VII8VIII9IX10X11XI12XII13XIII14XIV15XV16XVI17XVII18XVIII19XIX20XX21XXI22XXII23XXIII24XXIV25XXV26XXVI27XXVII28XXVIII29XXIX30XXX31XXXI32XXXII33XXXIII34XXXIV35XXXV36XXXVI37XXXVII38XXXVIII39XXXIX40XL41XLI42XLII43XLIII44XLIV45XLV46XLVI47XLVII48XLVIII49XLIX50L51LI52LII53LIII54LIV55LV56LVI57LVII58LVIII59LIX60LX61LXI62LXII63LXIII64LXIV65LXV66LXVI67LXVII68LXVIII69LXIX70LXX71LXXI72LXXII73LXXIII74LXXIV75LXXV76LXXVI77LXXVII78LXXVIII79LXXIX80LXXX81LXXXI82LXXXII83LXXXIII84LXXXIV85LXXXV86LXXXVI87LXXXVII88LXXXVIII89LXXXIX90XC91XCI92XCII93XCIII94XCIV95XCV96XCVI97XCVII98XCVIII99XCIX100C

Tens, hundreds and thousands

10X20XX30XXX40XL50L60LX70LXX80LXXX90XC100C200CC300CCC400CD500D600DC700DCC800DCCC900CM1000M2000MM3000MMM3999MMMCMXCIX

Step by step

Split the number into tens and units (99 = 90 + 9).
Write each part: 90 = XC, 9 = IX.
Join them: XCIX.

At a glance

Number	Correct	Not allowed
49	XLIX	IL
99	XCIX	IC
999	CMXCIX	IM