When designing a book, it is related to the size of a large piece of paper: 31x 43 (78.74 cm x109.22 cm). This paper is folded into two pages (four pages) at a time, which is called folio. Fold it in half again, and it becomes four (eight pages), which is called quarto. When it is folded in half again, it becomes eight pages (sixteen pages).

Fold it again and it will become sixteen (thirty-two pages), which is called sixteen, and so on. This is the historical origin of book size.

Extended data:

Precautions:

1. Shelf placement: Shelves for placing idle books are essential, and should be placed in a clean, dry, well-ventilated room that is not exposed to direct sunlight.

2. Anti-aging of books: The main reason for book aging is moisture, so anti-aging can be directly understood as moisture-proof, especially in rainy season in some areas, where the air humidity is quite high. You can properly select some substances that absorb moisture, such as silica gel desiccant and quicklime, and put them in boxes near the bookshelf. Once wet books are found, take them out and dry them with a hair dryer.

3. Books are for use, and it is inevitable that they will be stained with more or less dirt during use, but the method of removing dirt has to suit the remedy to the case. Oil stains need to be wiped with gasoline and dried, ink can be soaked with oxalic acid and then slowly absorbed with absorbent paper, and mildew spots can be wiped with ammonia water several times.