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.
Roman Numerals I = 1 C = 100 V = 5 D = 500 X = 10 M = 1000 L = 50 You can use a Roman numerals chart or conversion table to lookup Roman numerals or you can easily learn how to calculate them yourself with a few simple rules.