train mental calculation
About this app
A simple mental calculation trainer with this features:
- contains the four elementary arithmetic operations and the prime factorization - configurable task types and diffculty - configurable number input field - statistic about the performance - multi user support - time trial mode (solve as many tasks as possible within a defined time) with tasks depending on the wall clock time so that one can play "against" another one with the same tasks
Licensed under GPL-3.0-only.
What's New in v3.1
Imported from the F-Droid repository index.
- - monochrome icon
- - updated buildtools and dependencies
Version history
Sep 25, 2025 · 2.9 MB · Android API 23–36 · code 22
Imported from the F-Droid repository index.
- - monochrome icon
- - updated buildtools and dependencies
SHA-256 fbe87207c770a9df4fdf9231cea459287ca6fe4b38aaf580d08a8d3f7399c410
May 11, 2025 · 4.1 MB · Android API 21–35 · code 21
Imported from the F-Droid repository index.
SHA-256 cb8824d015a9dc2070c3db314cec641c099cd71eabe807353b5ae2dbdb8de054
May 22, 2022 · 2.4 MB · Android API 15–31 · code 20
Imported from the F-Droid repository index.
SHA-256 e0912e2cc5a0156f4e1faad5025892a3f435db9a3d5ca8a25909b68b4be1d474
Will it run on your device?
92%
- Runs on a broad range of modern Android versions.
- Multiple CPU architectures are covered.
- Aligned with the latest Android target SDK expectations.
Installation Guide
Open Settings on your Android device
Go to Security → Unknown sources (or Install unknown apps)
Enable "Allow from this source" for your browser or file manager
Open the downloaded APK file from your Downloads folder
Tap "Install" and wait for installation to complete
Launch the app from your home screen
Make sure to re-enable Unknown Sources restrictions after installation for security.
How to install this safely
How to verify the file you downloaded
Before you install anything, confirm the file is the one described here. On a computer, run shasum -a 256 your-download.apk (macOS or Linux) or certutil -hashfile your-download.apk SHA256 (Windows), then compare the output character-for-character with the SHA-256 on this page. If a single character differs, the file is not the build we recorded — delete it.
What the signing certificate proves
Every Android app is signed with a private key that only its developer holds. The fingerprint on this page is a hash of the matching public certificate, and it proves continuity rather than identity: it tells you a build came from whoever signed the earlier ones. Android enforces this at install time — if a package claiming to be com.rechnen.app is signed with a different key, the system will refuse to install it over your existing copy. A fingerprint that changes between releases is worth pausing on, because a repackaged app that has been modified by someone else cannot keep the original signature.
How to roll back to an earlier version
If the current release misbehaves, 3.0 is the last build before it. Android will not install an older version code over a newer one, so you must uninstall Calculate first — which clears its local data unless you have a backup. Reinstall the older APK only if its signing fingerprint matches the build you already trust, and check the API range: an older release may target an Android version your device has moved past.
Why we list sources instead of hosting everything
The official store channel is almost always the right choice: it updates automatically and carries the publisher's own distribution guarantees. A direct APK is useful when a device has no store access, when a rollout has not reached your region, or when you need a specific version — and only when the publisher has authorized that copy. APKBrowse does not list pirated, cracked, or unauthorized rebuilds of Calculate, and a listing is removed when the evidence for it stops holding up.
Get Calculate
Every source we list for com.rechnen.app is legality-reviewed. Pirated or cracked builds are never offered.
Other sources
F-Droid listing
officialF-Droid builds this app from source and signs it. This is its official listing, with older builds and full release notes.
Source code
verified publisherThe upstream repository this build is compiled from.
We check legality and signature continuity, but device behaviour still varies. Install at your own discretion.
App Information
Security Verification
We record provenance; we do not run malware scans. Verify the hash yourself before installing.
SHA-256 Hash
fbe87207c770a9df4fdf9231cea459287ca6fe4b38aaf580d08a8d3f7399c410
Signing certificate
5f1ab4b09546e0a971bc94c29a5adcff1b5b99a7279a7234d2eb16cfcf2a8b86
Permissions Required
Previous Versions
The signing certificate fingerprint for this release is on record, so a build that does not match it did not come from this publisher.
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