So, in a quite understandable need for distraction, you're doodling and thinking more about what the plural of "" series "" should be than about the topic at hand: "" serieses, "" "" seriese, "" "" seriesen, "" and "" serii? "" Or is it that the singular should be changed: one "" serie, "" or "" serum, "" just like the singular of "" sheep "" should be "" shoop. "" But the whole concept of things like 1 / 2 + 1 / 4 + 1 / 8 + 1 / 16 and so on approaches one, is useful if, say, you want to draw a line of elephants, each holding the tail of the next one: normal elephant, young elephant, baby elephant, dog-sized elephant,