7×7 Tales of a Sevensleeper
 Much to his brother's and parents' dismay, a boy's obsession over the habits of his favourite animals—squirrel-like creatures called "sevensleepers"—makes him pretend he is one of them. The number seven figures in his daily routines throughout the course of 49 stories: he becomes that age early on in the book, with as many presents to match; he goes to bed every night at seven o'clock; and he even eats or owns things in groups of seven. This trait even helps him follow the week more efficiently than months or years, which are both far longer.