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.
Timely arrival. Excellent quality product. Serves the purpose of catching up 10-12 year old kids with what has been covered so far at school. Helps as a refresher for adults too. Totally worth the price.