Site use conditions

Educational purpose

The content explains general mathematical methods. It does not provide individual financial, investment, tax, medical, legal, engineering or other professional advice. No professional relationship is created by reading the site, using its tools or sending a question.

Do not rely on an estimate or illustrative example for a safety-critical or legally significant decision. Check authoritative instructions and consult a suitably qualified professional where appropriate.

Examples and accuracy

Example prices, totals, serving quantities and other numerical scenarios are illustrative unless expressly described otherwise. They are not live product prices, offers, quotations or promises of savings.

The site aims to explain methods accurately, but content may contain errors or omissions. A correct mathematical procedure can also be inappropriate when the underlying assumptions do not fit your task. Verify units, starting amounts, rounding requirements and relevant conditions before relying on an answer.

You may report a possible error using the contact page. Identifying the page, calculation and proposed correction makes a report easier to assess. There is no guaranteed response or correction timetable.

Drafting tool

The contact tool formats text in your browser. It is not a messaging service and does not submit information to the site. Copy and download features depend on your browser and device settings. You are responsible for reviewing the draft and choosing whether and how to send it.

Do not enter confidential information that is unnecessary to describe your question. Keep control of downloaded files and clipboard contents, especially on shared devices.

Responsible use

Use the site lawfully. Do not attempt to disrupt its availability, interfere with its infrastructure, introduce malicious code or misuse contact channels. Feedback should relate to the site or its content and should not contain threats, abusive material or unsolicited advertising.

Content and third-party names

Original website text and design are protected by applicable intellectual-property law. Personal study, linking and uses permitted by law remain available. For substantial republication of original material, seek permission through the contact address.

Third-party photographs, names, trademarks and linked resources remain subject to their respective owners’ rights. Their appearance does not imply endorsement or affiliation. This site is not affiliated with Khan Academy, BBC, OpenStax, NRICH, The Open University, NIST, BIPM, Desmos or other referenced organisations.

External websites

External references are supplied for context and further learning. Their content, availability and policies are outside this site’s control. Follow their own conditions when using them. No affiliate relationship or paid placement is implied by a link.

Availability and legal limits

The site is provided without a promise of uninterrupted availability or suitability for every purpose. To the extent permitted by applicable law, no guarantee is made that all information or functionality is error-free. Nothing in these conditions excludes liability that cannot lawfully be excluded or removes mandatory legal rights.

Questions and changes

Contact [email protected] about these conditions. Conditions may be revised as the site changes. The version displayed on this page describes the current published site.