What if we consider the Euclidean algorithm using subtraction rather than division i.e.
we consider taking away x1 from x0 as one step and moving on from working with the
pair x0 and x1 to the pair x1 and x2 as one step. For example, consider again Example
2.2. We begin with 807. Taking away 673 from it leaves us with 134 which is smaller
than 673, so we can’t take anymore 673 from it lest it will become negative. We then