One Factorial — Privacy Policy

Last updated: August 10, 2026

One Factorial ("the app", "we", "us") is a math-practice app for elementary-school students. We built it to respect your privacy. This policy explains, in plain language, what information the app does and does not handle.

The short version

• No account or login is required.
• We show no ads and use no advertising or analytics trackers.
• We do not collect your name, email, phone number, or location.
• Your practice progress stays on your device.
• The only information that leaves your device is what's needed to process the optional one-time purchase.
• We never sell your data.

Information stored on your device only

The app remembers which problems you've solved so it can show a "Solved" mark and let you filter problems. This is stored locally on your device and is not transmitted to us or anyone else. You can erase it at any time using the "Reset progress" button in the app, or by uninstalling the app.

Purchase information

One Factorial offers a single optional one-time purchase that unlocks every problem in the app. Purchases are handled by your app store (Google Play or Apple App Store) and by our purchase-processing provider, RevenueCat. When you make or restore a purchase, the following is processed to deliver and protect that purchase:

• Purchase and receipt information (which product was bought, and whether it is active).
• A randomly generated, anonymous app-user identifier — not linked to your real identity.
• Basic technical information (such as device model, operating system, and IP address) used to process the transaction and prevent fraud.

We use this information only to unlock your purchase, let you restore it on a new device, and prevent abuse. Payment card details are handled entirely by the app store and are never seen by us.

Children's privacy

One Factorial is intended for children as well as parents and teachers. We do not knowingly collect personal information from children. The app has no accounts, no chat or social features, no ads, and no behavioral tracking. Any purchase must be made through the app-store account of a parent or guardian, subject to that store's parental-control and purchase-approval settings. If you believe a child has provided us with personal information, please contact us and we will delete it.

How information is shared

We do not sell or rent any information. Purchase-related information is shared only with the parties that make the purchase work: your app store and RevenueCat. We do not share information with advertisers or data brokers.

Data retention and deletion

On-device progress is kept until you reset it or uninstall the app. Purchase records are retained by the app store and RevenueCat as needed to keep your purchase valid and to meet their legal obligations. To request deletion of purchase-related data, contact us at the address below and we will assist.

Security

Information exchanged for purchases is transmitted over encrypted (HTTPS) connections. Because the app collects no accounts and no sensitive personal data, there is very little information to expose.

Third-party services

• RevenueCat — purchase processing.
• Google Play / Apple App Store — payment processing and app distribution.

Changes to this policy

We may update this policy as the app evolves. Material changes will be reflected by updating the "Last updated" date above.

Contact

Questions about this policy or your data? Email us at obretenov.martin@gmail.com.