For another example, when learning the understanding of derivatives, we can think that some words in life can be said backwards: "I'll be right on the road"-"I'll be right on the road", and some words can be written backwards: "Stone"-"Gan", "Swallow"-"Wu" and "Dull". Are these phenomena similar to the penultimate number?
For another example, when learning the meaning and writing of percentage, we can think of some idioms that can also be used to express percentage: as sure as a gun-90%, as obedient as a gun-100%, as accurate as a gun-100%, as dubious as a gun-50%, one in a hundred- ...........................