So let's begin by applying these rules in rule number one. Step number one, we estimate the PH at which the net charge and the protein would be zero. Now, at least in the beginning, before we gain intuition about how to solve these problems, we have to actually guess. So let's suppose our guess is PH of seven. Now, that guess might be wrong, and the only way to find out is to actually solve the problem. Let's suppose that our guess is a PH of seven.