Where the questions come from

The question bank

Each family started as a verified question. Muse Spark Open wrote a solver program for it, and the solver had to reproduce the verified answer on every variant. It also wrote programs for common wrong methods, and code checked that each one gives a different answer from the right one. For written questions the code is not stored, only these verification figures; for coding questions the solver code is kept and shown in each question's receipt.

Practising from your own notes? Bring your own question: upload one, and it goes through the same kind of check before you practise it.