There is not a business out there that sells its products or services to everyone. While I find this shocking, some people really don’t like chocolate. So, if you aren’t selling chocolate to everyone, who exactly are you selling it to? The 80/20 rule suggests that 80 percent of your sales are coming from 20 percent of your customers. In my experience, that is a pretty good estimate, although in some cases it looks more like a 90/10 rule.