With MC, ch 80.
Row 1 Sc in 2nd ch from hook and in each ch across 79 sc. *Mark this side as RS and mark center st. Ch 1, turn.
Row 2 Sc in each sc to one st before marked center st, (insert hook into st before center st, pull up loop, insert hook into center st, pull up loop, insert hook into st after center st, pull up loop, yarn over hook and pull through all loops on hook sc3tog = 2 sts decreased), sc in each sc to end of row. Ch 1, turn.
Following color sequence above, change to CC1, then repeat Row 2 until 3 sts remain. Sc3tog. Fasten off.
With MC, ch 40.
Row 1 (RS) Sc in 2nd ch from hook and in each ch across 39 sc; continue first row with RS facing by working sc into center st of initial ch row of Square #1 and in each st from center out to edge 79 sc.
Continue with directions for Square #1 from * to end of Square.
Repeat Square #2, but working 2nd half of first row across initial ch row of Square #2.
With RS facing and MC, sc across free half of Square #1 from outside edge to center, place center marker at center st, sc across free half of square edge of Square #3 79 sc.
Repeat Square #1 from * to end of Square.
When Square #4 is completed, inner square of Blanket is completed, assembled and ready for edging.
With RS facing and MC, work one rnd of sc around four sides of Blanket, working 3 sc into each corner st to turn corner neatly. Work 2 rnds sc with CC1, then 2 rnds sc with MC.
Weave in ends.