What Number Is Written XV in Roman Numerals?

The Roman numeral XV is the equivalent of the number 15. In the Roman numeral system, letters represent numerals. The basic letters and the numerals they represent are I equals one, V equals five, X equals 10, L equals 50, C equals 100, D equals 500, and M equals 1,000.

The rules applying to combination of letters prohibit the use of a particular letter more than three successive times within a number. When the value of a letter is the same or larger than the one immediately following it, the numbers are added. In the Roman numeral XV, X is larger than V, so the two are added together for a total of 15. When a letter has a smaller value than that of the letter immediately following it, the smaller value is subtracted from the larger value. In the Roman numeral IV, for instance, the I has a lower value than the V, so the one is subtracted from the five for a total value of four.