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.
In Roman numerals, X means 10 and L means 50, so XL is 50-10: 40.    Here's a lesson: I means 1. V means 5. X means 10. L means 50. I  think C means 100. Anyway, if I â¦say IV, that would mean 5 - 1,  because 1 (which has less of a value than 5) is on the left. VI  would be 5 + 1, because the number with a lesser value (1) is on  the right.