I'm not a math person so I can't answer your question as to how many. So I did it the simple way. When I put prairie points on a quilt, I first made the top. Next, I laid it out and started arranging points down one side how I wanted them to look. When I got to the end, I adjusted the points so they would come out at the end. I did the same for the short side, then doubled the figure. Only then did I truly know how many to make.