Just a warning to anyone thinking of using the Bond books for 11+ - I bought a bundle of these and have been firmly telling my kids that the answers in the book must be right... for NVR it's not always clear... but then my daughter said she KNEW she was right and the books were wrong, so I checked the first 20 in 'how to do maths and NVR'. 2 mistakes... I wrote to them about it, before reading on Amazon about the same book and someone's story...from 2016!!!) of writing in with the same mistakes. Their response seems to be that they consider this normal - they would have passed the feedback on to the editors, who have chosen to do nothing about it. No refund, either for me or the person in 2016. A refund is not really what I am after. They should not be selling these books that they have known for years have errors.