I have a weird WeChat username that includes a number, and I have a weird habit which is to change that number every day, usually following simple patterns like counting up or down in decimal, binary, base-6, base-5, and so on. My mom also have a weird habit, which is to track that number every day. So I wonder, why not turn this into a date-based rule-discovery game? You can check your answer with me once you think you get it.