I am having trouble finding the measurements for the square's size to be able to make a Disappearing Nine Patch square that will measure 12 and 1/2" (12" finished). If you have EQ or you are a great mathmetician, no I didn't say magician, I would appreciate any help you will share. I made the first ones using 4 and 1/2" squares and that came out too small and so I used 5" squares and they are too large. What size square is a girl to use??????