The Mathematics of Timekeeping: Gregorian Calendar Rules & Leap Seconds
Calculating exact age seems simple until you account for leap years, variable month lengths (28, 29, 30, 31 days), and daylight saving time shifts.
Longevity & Health
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The Gregorian Leap Year Rule Algorithm
Introduced by Pope Gregory XIII in 1582, the calendar rule states: A year is a leap year if it is divisible by 4, except when divisible by 100, unless it is also divisible by 400. Thus, the year 2000 was a leap year, 1900 was not, and 2400 will be.
Frequently Asked Questions
What is the difference between chronological age and biological age?
Chronological age counts elapsed calendar years from birth, whereas biological age reflects cellular health and biomarker degradation influenced by lifestyle, genetics, and diet.
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