While featuring the same keyboard arrangement and operating style made popular by previous ClassPad calculators, the fx-CP400 is also fitted with keys that slope down from bottom to top, which helps prevent input errors when pressing vertically arranged keys.
Once, when she turned to look out the window, I saw in the mirror the curved line of her forehead, the upward slant of the bottom of her nose, the little slope between her nostrils and her upper lip, and I was struck by the fine liveliness of her profile.