An android app for training mental calender caculations.
For more informations, please visit https://page.mi.fu-berlin.de/moritz/guessaday
Feel free to improve this app! You can open an issue here or make a pull request.
The app already supports all the languages in android for displaying the dates; you can help by translating the strings for the settings menu, by letting me know what all the phrases/words in the file strings.txt should be in your language!