Cut them 18X11, put a 2 1/2" strip of white on one narrow end. First column; Sew four together end to end. Second column; Cut a block in half crosswise. This is your first block so the blocks will be staggered. Sew the other half to the top end. Repeat from first column. Length will be 80", minus seams and the width will be 55" minus seams. So you'll have 78 1/2 X53, which will cover a hospital bed. 4 vertical blocks and 5 across uses your 20.