Quilt blocks for May's do. Good stitches

For May we were asked to make 12.5 inch blocks using green, white, black and gray. We had free reign on what design to use, so I decided to try out a postage stamp block. The more I see these the more I like them, I've started to cut my scraps into little squares to one day make something big with them. So I did my math very thoughtfully, used my new rotary cutter to cut precisely and sewed as carefully as can be, but my finished blocks were still only 11 inches. What? I have no idea. Quilting is a mystery wrapped in an enigma. I blame the math. So I added some white sashing to bring the blocks up to the required 12.5 inches. Done and done.