The equation is precise: current number (N) plus one equals salvation. This is the Rule of N – count the competitors, declare the number insufficient, and pronounce the market broken. The Rule of N never explains why the magic number varies by industry, or why it always happens to be exactly one more than we currently have. Few people will drive to another suburb just because a supermarket there is a bit cheaper this week. Likewise you don’t drive around a suburb looking for the cheapest petrol – you often go to the closest one.