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Corrections, suggestions and questions are all welcome. Email is the fastest way to reach us.
Last updated: October 19, 2026
What to include
To help us act quickly, mention the subject and chapter in your message:
- Corrections: the chapter name, the section (for example "Formulae" or "Key Points"), and what should change.
- Content requests: the subject, chapter and the topic you would like covered.
- Accessibility or bug reports: the device and browser you are using, and a short description of what went wrong.
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Before you write
Many common questions are already answered on the home page and on each chapter page. If you are looking for a specific formula or definition, try the search box on the maths or science index first.