Well, they do say to cut the yarn after the 2nd group of 10 bind off. That would work, then.
I think you gain the one stitch after the first bind off 10. After you bind off 10, you'd have one stitch on the right hand needle, then knit 23. You've got 24 stitches on the right hand needle now. Bind off the last 10 and cut the yarn.
Attach new yarn (same green color, a different color?) to the center 24 stitches, begin next row purling.