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 from 1 - 20: Roman Numerals Roman numerals The Roman numerals for numbers 1 to 20: 1 - I 2 - II 3 - III 4 - IV 5 - V 6 - VI 7 - VII 8 - VIII 9 - IX 10 - X 11 - XI 12 - XII 13 - XIII 14 - XIV 15 - XV 16 - XVI 17 - XVII 18 - XVIII 19 - XIX 20 - XX