1. The problem is to convert the Roman numeral XIX into a number. 2. Roman numerals are based on combinations of letters from the Latin alphabet: I, V, X, L, C, D, and M. 3. The values are: I = 1, V = 5, X = 10, L = 50, C = 100, D = 500, M = 1000. 4. When a smaller numeral appears before a larger one, it is subtracted; otherwise, it is added. 5. In XIX, we have X (10), I (1), and X (10). 6. The first X is 10. 7. The I is 1, and since it is before X (10), it is subtracted: 10 - 1 = 9. 8. So, XIX = 10 + 9 = 19. 9. Therefore, the number represented by XIX is 19.