Carroll's algorithm has evolved over the years. The First Sunday Doomsday Algorithm (https://firstsundaydoomsday.blogspot.com/2009/12/quick-start-guide.html htt

Carroll's algorithm has evolved over the years. The First Sunday Doomsday Algorithm (https://firstsundaydoomsday.blogspot.com/2009/12/quick-start-guide.html https://firstsundaydoomsday.blogspot.com/2009/12/quick-start...) includes all the improvements published as of 2023, including Fong & Walters' nifty "odd+11" rule for calculating the year code (https://arxiv.org/abs/1010.0765 https://arxiv.org/abs/1010.0765).