Comment answer: I used size 2 needles to get 8 stitches per inch and I cast on 72 stitches. My foot is like a size 8 1/2 shoe, so it depends on your foot size. The charts in the book can help you figure out how many to cast on and it also depends on the gauge of yarn you are using. Some yarns are thicker and some thinner and that would change your needle size and cast on.
I don't have a way to email the person who asked this question, so I hope you get this, Linda.