Pocket 991

A calculator that shows the way.

Follow highlighted keys through scientific-calculator operations. Tap HELP to ask a question or browse tutorials. Tap Take over whenever you want to continue yourself.

Need a hand?

For a bug or a question, email candlish.charles@gmail.com. Include your phone or tablet model, operating-system version, app version and the keys you pressed. iPhone and iPad beta testers can also send feedback through TestFlight.

Built-in tutorials and calculations work offline. On supported Apple devices, optional natural-language interpretation can use Apple’s on-device model. The Android build keeps local search, screen explanations and every built-in walkthrough, but does not include that optional Apple interpretation layer. On Android, use the microphone in your chosen keyboard if you want to dictate a question.

Pocket 991 is an independent educational recreation, not official calculator firmware. Some interfaces and numerical precision differ from physical calculators. It supports numerical calculus, not general symbolic algebra.

Effective 14 September 2026

Privacy policy

Pocket 991 is developed by Charlie Candlish. The app processes calculator input, tutorial questions and saved calculator state on your device.

Your calculations stay on your device

The app has no developer analytics, advertising, account registration or developer-hosted question service. Questions are not sent to a developer server. On supported Apple devices, optional language interpretation uses Apple’s on-device model. The Android app has no Internet permission and does not include that optional interpretation layer.

Optional dictation

On iPhone and iPad, choosing dictation requests microphone and speech-recognition access and uses on-device transcription. Audio is used to transcribe your question, and you can revoke those permissions in iOS Settings. The Android app does not request microphone permission itself; if you use your keyboard’s microphone, that keyboard and its provider handle dictation under their own settings and privacy terms.

Saved state and deletion

Calculator preferences and state are stored locally. Delete the app to remove its local data. Device backups are controlled through your Apple or Android settings.

Feedback you choose to share

Apple handles TestFlight feedback and diagnostics under its own terms. Google handles Play Store testing and operational data under its own terms. Feedback or diagnostics you deliberately send through those services may be available to the developer. If you email for support, the developer receives the information you include and uses it to respond and investigate the issue. Contact the email above to request deletion of your support correspondence.

This support website

This page has no advertising or app analytics. Its hosting providers may process standard connection information, such as IP addresses and request logs, to deliver and protect the website. Visiting this page does not send your calculator history or tutor questions.

Changes and contact

This policy will be updated if the app’s data practices change. For privacy questions, contact candlish.charles@gmail.com.