Excel's Date Parsing: A 400-Year-Old Bug?

While building Quadratic, an AI spreadsheet, the team uncovered bizarre quirks in Excel's date parsing. Entering "1/2" and adding 1 yields 45660; "10:75" becomes 0.46875. This stems from Excel's serial date system, counting days since January 1, 1900. However, historical inaccuracies (treating 1900 as a leap year and the Gregorian calendar shift) create discrepancies. Quadratic uses Rust's chrono library, avoiding these issues and integrating seamlessly with Python, SQL, and other modern tools. The team corrected the 1900 leap year error, restoring balance to the universe.