To calculate the overall star rating and percentage breakdown by star, we don’t use a simple average. Instead, our system considers things like how recent a review is and if the reviewer bought the item on Amazon. It also analyses reviews to verify trustworthiness.
I bought this book for my 9&11 year old boys to leaf through at breakfast or at night and my 11 year old tells me all these fun facts now after reading it. It's one of those fun books to have around and educational, without being boring. I like it.