I'm teaching my daughter to knit (and reminding myself how it's done). I remember my mother used to make blankets by knitting squares. And she always had a neat formula. One ball of wool, 50 stitches and it made a square. Or am I making it up? And if not, how big was the ball? This was in imperial measurements. The squares were pretty big. Or at lest they seemed big but then I was small.