Think Math Terms of Service
Last updated: May 20, 2026 (revised: added in-app purchase clause)
These Terms govern your use of "Think Math" (the "App"; distributed in Korea as "생각수학"), provided by Hasegi Inc. (the "Company"), and your rights, obligations, and responsibilities as a user. By installing and using the App, you agree to these Terms.
1. Services Provided
- Math concept exploration and educational content
- Wrong-note creation, management, and review (stored on-device; not transmitted externally)
- Handwriting and image attachment for wrong notes
- Local study-reminder notifications
- Advertising (supports the App)
2. User Account
The App does not require account registration. You may use the App immediately after installation. No login credentials are collected by the Company.
3. User Obligations
- You must comply with these Terms and applicable laws.
- You must not use the App for malicious purposes (hacking, reverse engineering, decompilation, unauthorized redistribution, etc.).
- You must not infringe any third party's intellectual property or other rights when using the App's features.
- Mobile data charges incurred while using the App are your responsibility.
4. Intellectual Property
- All content provided by the App (math concepts, problems, explanations, images, UI design, code, etc.) is owned by the Company or its licensors.
- You may not reproduce, distribute, transmit, publish, or create derivative works from the App's content for commercial purposes without prior written consent.
- Wrong notes, handwriting, attached images, and other content created by you remain your property.
5. User Data
- The App does not operate any server. All user-created data is stored only on the user's device and is not transmitted externally.
- You are solely responsible for managing data on your device. The Company is not liable for data loss caused by device damage, App uninstallation, OS reset, or similar events.
- If you wish to preserve important data, please make a separate backup.
6. Advertising
- The App displays ads through Google AdMob to support its operation.
- Advertisers are independent third parties; the Company is not responsible for ad content or for any transactions or interactions between users and advertisers.
- iOS users may choose whether to allow personalized ads via Apple's App Tracking Transparency (ATT) prompt.
- Users may permanently remove the banner ad and the rewarded-ad dialog through the in-app purchase described in Section 7 below.
7. In-App Purchases and Refunds
- The App offers a one-time, non-consumable in-app purchase "Think Math Pro" (product ID:
com.hasegi.thinkmath.pro). Upon purchase, the following benefits are permanently applied:
- All elementary / middle / high school concept cards permanently unlocked
- All facts in the water-droplet tab immediately available
- Banner ad removed
- Rewarded-ad dialog bypassed
- This is a one-time, permanent purchase — not a subscription. There is no auto-renewal or recurring charge. The purchase can be restored on other devices signed in to the same Apple ID or Google account via [Settings → Restore Purchases].
- All payments are processed through Apple App Store or Google Play. The Company does not directly collect or store any payment information (card numbers, bank details, etc.).
- Refunds follow the respective platform's refund policy. Refund requests cannot be made directly to the Company; please use the platform-specific procedures below.
8. Service Changes and Termination
- The Company may change, suspend, or discontinue all or part of the App for quality, operational, or legal reasons.
- Service may be temporarily limited due to maintenance, system inspection, network conditions, or third-party service (e.g., Google AdMob) outages.
- The Company is not liable for any damages arising from service interruption beyond what is required by applicable law.
9. Disclaimer of Warranty
The App is an educational reference tool. The Company does not guarantee any specific learning outcome, score improvement, or examination result from use of the App.
- The Company is not liable for service failures caused by force majeure (natural disasters, network outages, device issues, etc.).
- The Company is not liable for damages arising from the user's negligence.
- The Company has no obligation to intervene in disputes between users or between a user and a third party arising in connection with the App.
10. Limitation of Liability
The App is provided free of charge. To the maximum extent permitted by law, the Company's liability for any damages arising from use of the App is limited, except for damages caused by the Company's willful misconduct or gross negligence.
11. Changes to the Terms
- These Terms may be updated to reflect legal or service changes; updates will be announced through the App or this page.
- If you do not agree to the updated Terms, you may stop using the App and uninstall it. Continued use after the effective date constitutes acceptance of the updated Terms.
12. Governing Law and Jurisdiction
- These Terms shall be governed by the laws of the Republic of Korea.
- Any disputes shall be subject to the court with jurisdiction over the Company's principal office as the court of first instance.
13. Contact