I haven't read all the comments and answers prior to my post...but here is a tip that I will give you that is very important for a new knitter embarking on a scarf or anything like a wash cloth, dish towel, etc.
ALWAYS count your stitches at the end of every row.
This will reveal if you've lost any stitches (called dropped stitches)...or picked up any extra stitches (due to some mistake like knitting a stitch twice, or an unprescribed yarnover)
Better to catch the error at the end of the row in which the error occurred than many rows later.
ALWAYS check your work.
FYI: I still count my stitches for many projects. I use stitch markers to make this accounting quicker and easier.