The idea would be more obvious if `a` woldn't be exactly `2b` in this example (granted, author wasn't at liberty to choose values). Being previously unaware of what is Babylonian multiplication, it took me quite some time to get what exactly is being conveyed. It is too tempting to read it as "2 x 1" in this case, which doesn't register as a very notable generic discovery. I suspect many people who would find it otherwise interesting simply passed by before understanding what he is trying to show us.
