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.
How to Translate Roman Numerals. Roman numerals consist of a combination of the I, V, X, L, C, D and M letters. The position of the letters in relationship to each other is what determines the value of the actual Roman numeral.