
Excel incorrectly assumes that the year 1900 is a leap year - pcr910303
https://docs.microsoft.com/en-us/office/troubleshoot/excel/wrongly-assumes-1900-is-leap-year
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sloaken
This was to be compatible with the spreadsheet program called Lotus 123. At
the time microsoft made excel, Lotus was very popular. As such compatibility
was essential. Lotus 123 made the mistake.

