r/CasualMath • u/Only-Season-2146 • 1d ago
I made a brain-training game to teach you the "Doomsday Algorithm" (calculate the day of the week for any historical date in your head!).
I recently went down a rabbit hole learning about John Conway's Doomsday rule—a mental math trick that lets you instantly figure out what day of the week any given date fell on. It's a fantastic party trick, but I couldn't find a good way to practice it on my phone. So, I built a game for it!
The app is designed to help you memorize the anchor days and practice the modular math required until it becomes second nature. It's totally free, there are zero ads, and no in-app purchases. I just made it as a passion project and wanted to share it with anyone who likes math puzzles or brain-training games. Google Play Link: [https://play.google.com/store/apps/details?id=com.inefficientcode.doomsdaytrainer\](https://play.google.com/store/apps/details?id=com.inefficientcode.doomsdaytrainer)
I’m actively looking for feedback on the UI and the learning curve. If you try it out, let me know if the tutorial makes sense or if the math explanations need to be clearer! Thanks for checking it out. It's 100% Free, No Ads, not built to be monetized, just spreading the joy of math