PCO stands for Potential Change Order (construction management). Suggest new definition. This definition appears somewhat frequently and is found in the following Acronym Finder categories: 1  Business, finance, etc.
Quick Answer. The Roman numeral XIX is the number 19. X is the number 10, and I is the number one. When a lower number is placed in front of a larger number, it indicates subtraction; IX is the same as 10 minus one, which equals nine. The Ancient Romans used different letters to represent numbers.
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.