The Roman numeral "MCDLXV" represents the number 1465. In this numeral, "M" stands for 1000, "CD" represents 400 (500 minus 100), "L" is 50, "X" is 10, and "V" is 5. When these values are added together, they total 1465. Roman numerals are a numeral system originating from ancient Rome. They use combinations of letters from the Latin alphabet, specifically I, V, X, L, C, D, and M. This system was widely used throughout the Roman Empire and is still seen today in various contexts, such as clock faces and book chapters.