What does multiple of 18 + 1 mean?

I’ve been looking for some new patterns for blankets and i’ve stumbled on some great ones that have this:

Multiple of 9 +2 or Multiple of 10 +1, What does this mean and how can I make sure I CO enough stitches to make a decent size blanket for a baby or throw?

Thanks for your help!!!

It means cast on a multiple of 9 stitches (9, 18, 27, 36, 45, 54, etc) that will give you the width you want.

Then cast on 1 more. You’ll end up with 10 (19, 28, 37, 46, 55, etc) stitches. That extra stitch is probably for a border of some kind.

Thank you for responding. Now it makes sense.

Now more happy knitting for me!!! LOL

Thanks again!!