Biology question, help....?

Neurons have a resting cell membrane potential of about -70 mV. This does not tell you the actual charge either inside or outside the cell, it just tells you the difference in charge between them. To keep things simple, scientists generally consider the interior of the cell to be the difference (in this case, -70 mV) and the outside 0 mV. In almost all cells, there is more sodium and chlorine outside the cell than inside, and more potium inside the cell than outside.