Hi, I am a little foggy at figuring this out right now. I am making a baby blanket-- cutting solid block at 6 1/2 "; and need alternate block - pinwheel to end up same size. Do I cut pinwheel blocks 4 1/2 " and then make 1/2 square triangles from them ? I don't have alot of fabric to waste on errors so will the 4 1/2 " block come out right?? I want 6" finished blocks in the end. Thank you, Elaine