A couple of months ago I posted a Calender Math Freebie.
I've been using this as a center in Math every week with my students. (It's great because the responses are different every day!) We recently had our 100th day of school, and that's when I realized the glitch. My calendar center has a section that focuses on counting up to the 100th day of school. I've now added a 2nd page to the freebie that can be used after the 100th day of school. It's free for download on Teachers Notebook or from my Google Drive account. Enjoy!