Terms of use
Published .
These terms cover the Sumi app and this website, which are made by Tomu Ozawa. By using Sumi, you agree to them. If you downloaded Sumi from the App Store, Apple’s standard licence agreement also applies.
Using Sumi
Sumi is free to use for study, work and everyday sums. Every calculator feature is free, and there are no ads, subscriptions or accounts.
Check results that matter
Sumi is built to give correct answers, but like any calculator it can be wrong, and sums can be entered wrongly. Decimal answers are rounded, and SOLVE, integrals and derivatives are found numerically, so their results are approximations.
If a result matters for money, health, safety, engineering or anything else important, check it another way. Don’t rely on Sumi alone where a mistake could cause harm.
Exams
Sumi runs on a phone or tablet. Most school and university exams don’t allow phones, so check your exam’s rules.
Tips
Tips are optional one-time purchases. They unlock nothing and don’t change what Sumi does. Google Play or the App Store handles payment, receipts and refunds under its own terms.
Changes and availability
Sumi is provided as it is. Features may change or be removed, and the app or this website may sometimes be unavailable.
Liability
As far as the law allows, the developer isn’t liable for losses that come from relying on a result from Sumi, or for indirect or consequential losses.
Nothing in these terms limits liability for death or personal injury caused by negligence, for fraud, or for anything else the law doesn’t allow to be limited. Nothing in them affects your rights as a consumer.
Fonts and icons
Sumi and this website use Inter, Noto Sans Math and Geist under the SIL Open Font License: read the licences for Inter, Noto Sans Math and Geist. The app’s icons are Material Icons by Google, under CC BY 4.0. Settings → Licences in the app lists everything it includes.
Changes to these terms
If these terms change, this page will be updated and the date above changed.
Law
These terms are governed by the law of England and Wales. If you live elsewhere, you keep the protection of your local consumer law and can bring a claim in your local courts.
Contact
Questions about these terms can be sent to hello@sumicalculator.com.