Some simple back-of-the-envelope calculations can help you understand a business. It’s most obvious in a small business. Say, a one-man business. Magician Evan Northrup and I sat down to talk about his business and how it works. He graciously allowed me to share the video. In the first half, we walk through the basic numbers of the business. In the second half, we ask how to make his product stand out from his competition.