Dr. Sarah Jenkins

Ph.D. in Applied Mathematics, ISO-8601 Research Fellow

Chronology specialist and computational mathematician with over 14 years of experience researching calendar standards, astronomical time-reckoning, and date algorithms.

Articles by Dr. Sarah Jenkins (2)

Date & Calendar Math

How Gregorian Leap Years Actually Work: The 400-Year Cycle Explained

Why are some century years like 2000 leap years while 1900 and 2100 are not? Explore the astronomical math and history behind the Gregorian calendar leap rule.

Sep 25, 2026 Read Guide →

Date & Calendar Math

ISO-8601 Explained: Why Week 1 of a Year Can Begin in December

Demystifying the international ISO-8601 standard. Discover why the ISO week-year can differ from the calendar year and how weeks are numbered globally.

Sep 25, 2026 Read Guide →