Can anyone tell me how to work out a score. If they do 80 questions, how many do they need to get right to get 121? I realise it is then standardised but is they anyway when you are practising to see how they are doing?

If it is for Bucks, I always worked on the basis of needing around 92% to be (slightly) on the safe side. You can sort of work it out from the scores in some of the Bucks posts in the appeal section where you can see the number of questions children got right and the overall score they were awarded. The scores are standardised according to age, so it is not an exact science.

I expect someone, somewhere will be able to give a more specific answer!

Taking the average 11+ child as 10 years 6 months, a score of 121 would be achieved with 73 correct answers out of 80 questions.

Orson - that's just a guess. The actual raw score varies from year to year depending on the cohort.

Of course it varies depending on the cohort so this is not a definitive answer.
Based on the evidence available, however, it is a good 'guide' as to the required score.

CATs are standardised in a completely different way; they bear little relation to the Bucks 11+.

I'm going on the Glos 11+