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Numbers & Letters

Mental arithmetic and vocabulary game, no ads, no trackers
New in version 1.133
French dictionary: conjugated verb forms removed. Hard letters (H, J, K, Q, W, X, Y, Z) are drawn less often in French. At the end of a round, the button to continue now replaces the Submit button. Streak and timed challenge trophies for 12 and 15 at Mathieu level moved up to Ruby and Diamond.
Numbers & Letters is a mental arithmetic and vocabulary game, in the spirit of the well-known French TV game show of the same principle, with no affiliation to it.

Two game modes:

* Numbers: 6 numbers are drawn along with a target to reach. Build your calculation step by step, calculator-style, combining the numbers with the 4 basic operations.
* Letters: 10 letters are drawn. Find the longest possible word using these letters before time runs out.

Several ways to play:

* Solo game, with 4 levels of increasing difficulty (Emile, Nestor, Monique, Mathieu), alternating numbers and letters rounds.
* Duo game, for two players on the same phone, with a Duo mode (each keeps their own score) or a Head-to-head mode (only one winner per round).
* Network game, the same duo game but on two separate phones, connected over Wi-Fi or Bluetooth.
* Daily challenge, with a randomly drawn goal each day and trophies for streaks of successful days.
* Streak, timed, words and no-mistake challenges, to progress at your own pace.
* Free training mode, with no time limit and no round limit.

The app keeps track of your statistics and rewards your progress with trophies, offers a light or dark theme, and works entirely offline: no ads, no trackers, no network connection required (except to play a network game).

Free and open source software under the GNU GPL-3.0 license.

Versions

Although APK downloads are available below to give you the choice, you should be aware that by installing that way you will not receive update notifications and it's a less secure way to download. We recommend that you install the F-Droid client and use that.

Download F-Droid
  • Version 1.133 (134) suggested Added on Oct 14, 2026

    arm64-v8a armeabi-v7a x86 x86_64

    This version requires Android 13 or newer.

    It is built and signed by F-Droid, and guaranteed to correspond to this source tarball.

    Permissions
    • view network connections
      Allows the app to view information about network connections such as which networks exist and are connected.
    • view Wi-Fi connections
      Allows the app to view information about Wi-Fi networking, such as whether Wi-Fi is enabled and name of connected Wi-Fi devices.
    • connect to paired Bluetooth devices
      Allows the app to connect to paired Bluetooth devices
    • discover and pair nearby Bluetooth devices
      Allows the app to discover and pair nearby Bluetooth devices
    • allow Wi-Fi Multicast reception
      Allows the app to receive packets sent to all devices on a Wi-Fi network using multicast addresses, not just your phone. It uses more power than the non-multicast mode.
    • run foreground service
      Allows the app to make use of foreground services.
    • have full network access
      Allows the app to create network sockets and use custom network protocols. The browser and other applications provide means to send data to the internet, so this permission is not required to send data to the internet.
    • interact with nearby Wi-Fi devices
      Allows the app to advertise, connect, and determine the relative position of nearby Wi-Fi devices
    • show notifications
      Allows the app to show notifications
    • run at startup
      Allows the app to have itself started as soon as the system has finished booting. This can make it take longer to start the phone and allow the app to slow down the overall phone by always running.
    • prevent phone from sleeping
      Allows the app to prevent the phone from going to sleep.
    • fr.pierre.chiffreslettres.DYNAMIC_RECEIVER_NOT_EXPORTED_PERMISSION

    Download APK 36 MiB PGP Signature | Build Log

  • New in version 1.132
    The app now falls back to English instead of French when the system language is not supported.
  • Version 1.132 (133) - Added on Oct 12, 2026

    arm64-v8a armeabi-v7a x86 x86_64

    This version requires Android 13 or newer.

    It is built and signed by F-Droid, and guaranteed to correspond to this source tarball.

    Permissions
    • view network connections
      Allows the app to view information about network connections such as which networks exist and are connected.
    • view Wi-Fi connections
      Allows the app to view information about Wi-Fi networking, such as whether Wi-Fi is enabled and name of connected Wi-Fi devices.
    • connect to paired Bluetooth devices
      Allows the app to connect to paired Bluetooth devices
    • discover and pair nearby Bluetooth devices
      Allows the app to discover and pair nearby Bluetooth devices
    • allow Wi-Fi Multicast reception
      Allows the app to receive packets sent to all devices on a Wi-Fi network using multicast addresses, not just your phone. It uses more power than the non-multicast mode.
    • run foreground service
      Allows the app to make use of foreground services.
    • have full network access
      Allows the app to create network sockets and use custom network protocols. The browser and other applications provide means to send data to the internet, so this permission is not required to send data to the internet.
    • interact with nearby Wi-Fi devices
      Allows the app to advertise, connect, and determine the relative position of nearby Wi-Fi devices
    • show notifications
      Allows the app to show notifications
    • run at startup
      Allows the app to have itself started as soon as the system has finished booting. This can make it take longer to start the phone and allow the app to slow down the overall phone by always running.
    • prevent phone from sleeping
      Allows the app to prevent the phone from going to sleep.
    • fr.pierre.chiffreslettres.DYNAMIC_RECEIVER_NOT_EXPORTED_PERMISSION

    Download APK 36 MiB PGP Signature | Build Log

  • New in version 1.94
    Daily reminder is now optional (dedicated setting, notification permission requested only when enabled); new profiles default to the phone's language.
  • Version 1.94 (95) - Added on Oct 08, 2026

    arm64-v8a armeabi-v7a x86 x86_64

    This version requires Android 13 or newer.

    It is built and signed by F-Droid, and guaranteed to correspond to this source tarball.

    Permissions
    • view network connections
      Allows the app to view information about network connections such as which networks exist and are connected.
    • view Wi-Fi connections
      Allows the app to view information about Wi-Fi networking, such as whether Wi-Fi is enabled and name of connected Wi-Fi devices.
    • connect to paired Bluetooth devices
      Allows the app to connect to paired Bluetooth devices
    • discover and pair nearby Bluetooth devices
      Allows the app to discover and pair nearby Bluetooth devices
    • allow Wi-Fi Multicast reception
      Allows the app to receive packets sent to all devices on a Wi-Fi network using multicast addresses, not just your phone. It uses more power than the non-multicast mode.
    • run foreground service
      Allows the app to make use of foreground services.
    • have full network access
      Allows the app to create network sockets and use custom network protocols. The browser and other applications provide means to send data to the internet, so this permission is not required to send data to the internet.
    • interact with nearby Wi-Fi devices
      Allows the app to advertise, connect, and determine the relative position of nearby Wi-Fi devices
    • show notifications
      Allows the app to show notifications
    • run at startup
      Allows the app to have itself started as soon as the system has finished booting. This can make it take longer to start the phone and allow the app to slow down the overall phone by always running.
    • prevent phone from sleeping
      Allows the app to prevent the phone from going to sleep.
    • fr.pierre.chiffreslettres.DYNAMIC_RECEIVER_NOT_EXPORTED_PERMISSION

    Download APK 36 MiB PGP Signature | Build Log