The Roman numeral "CCCLXV" represents the number 365. In this numeral, "CCC" stands for 300, "LX" represents 60, and "V" equals 5. When combined, these values add up to 365, which is commonly recognized as the number of days in a year. The significance of 365 days is evident in the Gregorian calendar, which is widely used today. This calendar system, introduced by Pope Gregory XIII in 1582, helps to keep track of time and the changing seasons. The leap year, occurring every four years, adds an extra day to account for the Earth's orbit around the Sun.