I was confused about those 2 rows when I made that as well - in fact, I posted about it on here.
It should be:
Row 40: cast on 12 stitches, knit across (52)
Row 41: cast on 12 stitches, knit across (64)
They combined the two rows into one line becuase you're doing the same action, but it confused a newbie like me.