Yup and if you need a right angle, combine it with this https://news.ycombinator.com/item?id=48538771 https://news.ycombinator.com/item?id=48538771 by roelsch

Yup and if you need a right angle, combine it with this https://news.ycombinator.com/item?id=48538771 https://news.ycombinator.com/item?id=48538771 by roelschroeven. I often wondered how to ensure that the corners of a sheet of paper make a right angle. You need that to form a square sheet, otherwise the standard trick of folding along the diagonal gives a rhombus, not a square.