In the mid-1970s, my family had a dog named Pippin. As we three kids got older, we took on more responsibilities for chores, and for feeding Pippin, we came up with the following method to keep track of whose turn it was to feed him: We would divide the date by three and check the remainder. If it was zero, then it was Sara's turn. If it was one, then it was Ruth's turn. If it was two, then it was my turn. In months with 31 days, as well as on 28 February, it was my mother's turn. And every four years, on 29 February, it was my father's turn. (Andrew Shields, #111Words, 10 July 2026)