Status of these claims
Target, not certificate. The site aims to meet WCAG 2.2 Level AA. It has not been through a formal accessibility audit and is not certified as conforming. Nothing on this page should be read as a conformance statement, and no third-party evaluation has been obtained.
The guidance followed is the W3C's Web Content Accessibility Guidelines 2.2, a Recommendation dated 12 December 2024. Its age does not make it obsolete: the WCAG 3.0 publication dated 10 September 2026 is still a Working Draft, not a replacement conformance standard. Sources were reviewed on 18 September 2026.
Local automated browser checks and a code review of these pages have been carried out, including keyboard interactions, responsive layouts and axe accessibility scans. These are development checks only: they are not a professional accessibility audit and not a certification. Automated scans cannot establish full conformance; unresolved contrast checks, assistive-technology testing and real-device review still require human evaluation.
What is implemented by design
| Area | What the site does | Why it matters |
|---|---|---|
| Structure | Every page uses one main landmark, a header, a footer and labelled navigation regions, with one first-level heading and headings nested in order. | Screen reader users can jump between regions instead of reading everything. |
| Skip link | A "Skip to content" link is the first focusable element and points at the main region. | Keyboard users can bypass repeated navigation. |
| Keyboard operation | Every control is a real button, link, checkbox or input, reachable and operable with the keyboard alone, with no keyboard traps. | Many users navigate without a pointer, and some cannot use one. |
| Focus visibility | Interactive elements keep a visible focus indicator that is not removed by styling. | Keyboard users need to see where they are. |
| Labels and instructions | Inputs have programmatic labels and hints, and errors are written as plain-language text rather than colour alone. | A message that relies on colour is invisible to some users. |
| Reduced motion | Animations are suppressed or shortened when the operating system requests reduced motion. | Motion can cause discomfort or distraction. |
| Text alternatives | Decorative graphics are hidden from assistive technology, and any meaningful diagram has a text table carrying the same information. | Equivalent information must be available in text, not only in a picture. |
| Contrast and sizing | Body text, controls and focus indicators are designed for AA contrast levels, with a minimum target size for tap controls. | Low contrast and tiny targets exclude users with low vision or limited dexterity. |
| Zoom and reflow | The layout is designed to remain usable when text is enlarged and when the viewport is narrow, with wide tables placed in scrollable containers. | Enlarged text must not clip or overlap content. |
| Theme choice | A light and a dark theme are both available, and the choice is announced by a labelled button. | Light sensitivity and low vision needs vary by person and setting. |
The diagram, specifically
The interactive prime-exponent diagram on the calculator, explained in the method guide, is deliberately limited. The drawing is a schematic: blocks represent prime exponents rather than the magnitude of a number, so it is never drawn to scale. It is marked decorative for assistive technology, and it is capped to the first three numbers and the first six primes so it stays legible when enlarged.
Because a drawing is a poor way to convey exact data, the same information is provided twice in text — once as a table of exponents and once as a short reading guide that states which highest power wins. A reader who never sees the image loses no mathematical information.
Long numbers and worked solutions
LCM results can be very long. The 100-digit limit applies to each input, not to the result: an LCM can be far longer than any single input, and the examples page shows one result as a 199-digit expression. To keep those values usable with magnification and narrow viewports:
- Long results are allowed to wrap instead of forcing the whole page to scroll sideways.
- Wide tables sit inside a scrolling container so the page around them does not shift.
- In the static worked example on the examples page, an extremely large value is written in a power form, such as 10¹⁹⁸ + 4 × 10⁹⁹ + 3, because an unwrapped digit string is hard to verify visually. This is a written illustration, not automatic result formatting: the calculator reports long results as digits and does not rewrite them into power form for you.
What has not been verified
- No formal audit. The site has not been tested by an accessibility professional, and no automated-and-manual audit report exists for it.
- No user testing with disabled participants. No sessions with assistive-technology users have been run for this build, so the design reflects known good practice rather than confirmed user experience.
- Assistive-technology variation. Behaviour differs between screen readers, browsers and operating systems. Features that work well in one combination may behave differently in another, and this has not been exhaustively tested.
- Local-file use. Some browser features — including storage and focus behaviour — can behave differently when a page is opened directly as a file rather than served over the web. If something behaves oddly, trying a served copy is a reasonable first step.
- Content complexity. Mathematical explanations and long tables remain inherently demanding. The pages simplify where possible and label conventions clearly, but no educational page can remove the difficulty of the underlying subject.
- Third-party links and advertisements. External sources and banner creatives are controlled by third parties and have not been assessed here. The banner above the footer is labelled Advertisement and scales down to fit narrow screens; its text, animation and keyboard behaviour depend on the provider.
Testing you can do yourself
- Press Tab from the top of any page and confirm the skip link appears first, then the header controls, then the navigation.
- Operate the theme toggle, the mobile menu button and every input using only the keyboard.
- Enlarge the text to 200% and check that no content is cut off or overlapping.
- Turn on the operating system's reduced-motion setting and confirm the pages feel calm and still.
- Read the diagram section aloud from the text table and confirm the same conclusion is reachable.
If something does not work
You can report an accessibility barrier on GitHub. Include the page, browser, assistive technology if relevant, and steps to reproduce. GitHub requires an account and issues are public; do not include personal information. An account-free, private accessibility contact channel is not available yet. If the interactive diagram is difficult to use, choose “Explore the diagram data” for the equivalent text table, or read the static method guide and worked examples. These alternatives do not resolve every possible barrier. See the terms of use and privacy page for further context.