Convert number: 18 in Roman numerals, how to write?

18 written in Roman numerals

Roman numerals used to make the conversion:

I = 1; V = 5; X = 10;


Reading rules


1. Break the number (decompose it).

Break the number (decompose it) into place value subgroups:

18 = 10 + 8;


2. Convert each subgroup.

Convert each subgroup to Roman numerals:

10 = X;


8 = 5 + 1 + 1 + 1 = V + I + I + I = VIII;


3. Wrap up the Roman numeral.

Substitute the Roman numerals for each subgroup:

18 =


10 + 8 =


X + VIII =


XVIII;


XVIII is a group of numerals in additive notation.

Additive notation of the Roman numerals


Final answer:

How to convert the number 18?
18 written in Roman numerals:
18 = XVIII

XVIII is a group of numerals in additive notation.

Additive notation of the Roman numerals


More operations of this kind:

17 = ? ... 19 = ?

Online converter of Arabic numbers to Roman numerals

Latest conversions of Arabic numbers to Roman numerals

18 = XVIII Oct 18 16:10 UTC (GMT)
1,763 = MDCCLXIII Oct 18 16:10 UTC (GMT)
1,490 = MCDXC Oct 18 16:10 UTC (GMT)
143,820 = (C)(X)(L)MMMDCCCXX Oct 18 16:10 UTC (GMT)
1,754 = MDCCLIV Oct 18 16:10 UTC (GMT)
576,203 = (D)(L)(X)(X)(V)MCCIII Oct 18 16:10 UTC (GMT)
135 = CXXXV Oct 18 16:10 UTC (GMT)
7,328 = (V)MMCCCXXVIII Oct 18 16:10 UTC (GMT)
1,980 = MCMLXXX Oct 18 16:10 UTC (GMT)
1,457 = MCDLVII Oct 18 16:10 UTC (GMT)
1,100 = MC Oct 18 16:10 UTC (GMT)
125,808 = (C)(X)(X)(V)DCCCVIII Oct 18 16:10 UTC (GMT)
459 = CDLIX Oct 18 16:10 UTC (GMT)
converted numbers, see more...

The set of basic symbols of the Roman system of writing numerals

The major set of symbols on which the rest of the Roman numberals were built:

  • I = 1 (one); V = 5 (five);

  • X = 10 (ten); L = 50 (fifty);

  • C = 100 (one hundred);

  • D = 500 (five hundred);

  • M = 1,000 (one thousand);

    • For larger numbers:

    • (*) V = 5,000 or |V| = 5,000 (five thousand); see below why we prefer this notation: (V) = 5,000.

    • (*) X = 10,000 or |X| = 10,000 (ten thousand); see below why we prefer this notation: (X) = 10,000.

    • (*) L = 50,000 or |L| = 50,000 (fifty thousand); see below why we prefer this notation: (L) = 50,000.

    • (*) C = 100,000 or |C| = 100,000 (one hundred thousand); see below why we prefer this notation: (C) = 100,000.

    • (*) D = 500,000 or |D| = 500,000 (five hundred thousand); see below why we prefer this notation: (D) = 500,000.

    • (*) M = 1,000,000 or |M| = 1,000,000 (one million); see below why we prefer this notation: (M) = 1,000,000.

(*) These numbers were written with an overline (a bar above) or between two vertical lines. Instead, we prefer to write these larger numerals between brackets, ie: "(" and ")", because:

  • 1) when compared to the overline - it is easier for the computer users to add brackets around a letter than to add the overline to it and
  • 2) when compared to the vertical lines - it avoids any possible confusion between the vertical line "|" and the Roman numeral "I" (1).

(*) An overline (a bar over the symbol), two vertical lines or two brackets around the symbol indicate "1,000 times". See below...

Logic of the numerals written between brackets, ie: (L) = 50,000; the rule is that the initial numeral, in our case, L, was multiplied by 1,000: L = 50 => (L) = 50 × 1,000 = 50,000. Simple.

(*) At the beginning Romans did not use numbers larger than 3,999; as a result they had no symbols in their system for these larger numbers, they were added on later and for them various different notations were used, not necessarily the ones we've just seen above.

Thus, initially, the largest number that could be written using Roman numerals was:

  • MMMCMXCIX = 3,999.

Roman numerals reading rules, summary:

I. The Roman numerals set of basic symbols

II. The rule of numerals repetition

III. Subtractive notation of the Roman numerals

IV. Additive notation of the Roman numerals


How to convert Hindu-Arabic numbers to Roman numerals: breaking down into place value subgroups

Examples of converting Hindu-Arabic numbers to Roman numerals


Roman numerals from 1 to 100

Roman numerals from 1 to 1000

Mathematical operations with Roman numerals:

I. Addition. Learn by example how to add Roman numerals the right way, like the Romans calculated, steps, explanations

II. Subtraction. Learn by example how to subtract Roman numerals the right way, like the Romans calculated, steps, explanations

III. Addition and subtraction. Learn by example how to add and subtract Roman numerals the right way, like the Romans calculated, steps, explanations