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 IX or ix represents the number 9. Which is so true, it represents the number 9. Roman numerals are; I = one[1], V = five[5], X = ten[10], L = fifty[50], C = one hundred[100], etc. These are the symbols the Romans used. Which is the bases of there numbering system.