I don't understand the protein/dollar column. Flour has protein listed as "3" and price as 1.68 but I can't see how to get 134 protein/dollar from these numbers. The calorie/dollar column works the way you would expect.
Good question. There's data missing in the table to determine how that column is calculated. Essentially, it's how much protein you would get in that total amount of calories while "protein" is how much protein you would get in a single serving. I looked at eggs and that's how things made sense.