



 
Jenalee, If day 0 is Monday, then days 1, 2, 3, 4, 5, 6 are Tuesday, Wednesday, through Sunday, respectively. The next week, starting on Monday, is days 7, 8, …, 13. If you reduce those numbers modulo 7, you get 0, 1, …, 6 all over again. The same thing happens for the next week, and the next, and the next … Does that help? —Victoria  


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