Above GCSE B grade in difficulty
Murderous Maths like in style ,or similar idea.
The book is for a young mathematician who is thirst for more expanding knowledge, but don't want to be trapped in exam route.
I don't have anything marked GCSE at home, just teacher told me his level is GCSE B.
The reason I start the thread here is I believe Home ed children's parents got more ideas than the exam orientated school teachers.