Eight Pills
The world of alchemy could get very complicated, very quickly. However the one thing that wouldn't change was the foundation of a product's purity and what kind of reaction it would thus elicit.
The number one goal of every alchemist was to create a pill or potion with the lowest amount of impurities possible. And, of course, impurities were measured in percentages.
The minimum threshold one needed to reach for a pill or potion to be viable was 51%. This was considered the entry stage and upon succeeding, one could finally name themselves the equivalent grade of alchemists.
However, the reality was that most cultivators, unless they were desperate, wouldn't dare to consume such a pill or potion. Such pills were usually fed to low grade beasts who only performed hard, labor intensive tasks, or they were sold off to poor cultivators who had no other choice remaining.