I am doing this scarf but have run into trouble on Row 9 - it just doesn't work. I've counted and I have the correct number of stitches on needles between the 3 stitch edges. Now I have to do 4 stitches on the edge and nothing works out.
Instead of counting stitches, start at the beginning of the row and name them - edge st, k yo dec, 3 knits... however the pattern goes. That way you can easily see if you forgot to you or did an extra dec. The stitch numbers do change from row to row, so that may be throwing you off.