A note on yarn, gauge, and joining in the round: A word of warning on the Size Q crochet hook -- it's easy to get a wide variety of gauges with this hook because of it's large size. I have a tendency to crochet pretty tightly with this hook, so your size may come out a little larger. Note though, however, with my gauge, I was able to use exactly 3 skeins of Vanna's Choice yarn so you may need more yarn if you crochet a little looser with this hook. If you're worried about going over the amount of yarn, you can start off with fewer chains in the beginning round (i.e., chain 100 instead of 104). Also, the pattern is worked in the round, but more specifically, it's joined in the round and then the scarf is turned to create a pattern that looks more identical to what it would look like if the scarf was worked flat.
Ch 104 chains loosely and join in round with a slip stitch, being careful not to twist.
Round 1: Chain 2. DC in next ch space and in each ch across to end. Being careful not to twist the chain, SL ST into first DC (which is the first ch 3) to join chains in the Round. Turn. Count your stitches at this point. You should have about 103 stitches at this point. If you don't, that's okay, just be consistent with your number for the rest of the rows as each row should have the same number of stitches.
Round 2: Chain 2. DC in each DC from previous row. SL ST to first stitch to join in the round. Turn.
Rounds 3-6: Repeat Round 2. On Row 6, SL ST into first stitch to join and finish off. Weave in the loose ends.
Ch = Chain
DC = Double Crochet
SL ST = Slip Stitch