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.
Xi (uppercase Î¾, lowercase Î¾; Greek: Î¾Î¹) is the 14th letter of the Greek alphabet. It is pronounced [ksi] in Modern Greek, and generally /ËzaÉª/ or /ËsaÉª/ in English. In the system of Greek numerals, it has a value of 60. Xi was derived from the Phoenician letter samekh .