Accuracy and corrections

Accuracy is the whole product, so here is exactly what we do and what we do not do.

What every question goes through

1. It is written from the public content specification, as an original question, with a worked solution. Nothing is copied or closely paraphrased from official papers, live tests or other providers.
2. A script recomputes the answer from the problem data alone, with exact arithmetic or by checking every case, and confirms that exactly one option is correct and the others are wrong.
3. Independent AI solvers then answer the question from the wording alone, without seeing our answer, and a further AI pass reads every worked solution line by line. Any disagreement sends the question back to step 1.
4. The owner approves each batch before it goes live.

What we have not done

The questions have not yet been reviewed by a qualified maths teacher or tutor. Steps 2 and 3 are automated checks, which catch most mistakes but are not a substitute for a human examiner. We will say so here when a human review has taken place.

If you find a mistake

Use the Report a mistake link on the question, or email [email protected]. We check every report. A confirmed mistake is fixed or the question is withdrawn, it is listed below, and you can have a full refund at any time while your access lasts.

Corrections log

No corrections so far.

Last updated 2026-11-12.