>>70602987The ISO 216 paper size system uses an aspect ratio of √2:1, meaning that you can fold a sheet in half to yield a rectangle with half the area and exactly the same aspect ratio. This also makes it easier to add inserts to folded booklets by selecting the next size down within each series (A, B, C). Additionally, this consistent aspect ratio makes it easier to scale pages up and down to print in different formats and sizes. The so-called "silver ratio" of √2:1 is the only one with this property.
