Editing ISO 216 (section)

==Application==

The ISO 216 formats are organized around the ratio 1:{{math|{{sqrt|2}}}}; two sheets next to each other together have the same ratio, sideways. 

In scaled photocopying, for example, two A4 sheets reduced to A5 size fit exactly onto one A4 sheet, and an A4 sheet in magnified size onto an A3 sheet; in each case, there is neither waste nor want.

The principal countries not generally using the ISO paper sizes are the United States and Canada, which use [[Paper size#North American paper sizes|North American paper sizes]]. Although many Latin American countries have also officially adopted the ISO 216 paper format, Mexico, Panama, Peru, Colombia, the Philippines, and Chile also use mostly U.S. paper sizes.

[[Rectangle|Rectangular]] sheets of paper with the ratio 1:{{math|{{sqrt|2}}}} are popular in [[paper folding]], such as [[mathematics of paper folding|origami]], where they are sometimes called "A4 rectangles" or "silver rectangles".<ref name="Lister">{{cite web|url=http://www.britishorigami.info/academic/lister/a4.php|title=The A4 rectangle|last=Lister|first=David|work=The Lister List|publisher=British Origami Society|location=England|access-date=6 May 2009}}</ref>  In other contexts, the term "silver rectangle" can also refer to a rectangle in the proportion 1:(1&nbsp;+&nbsp;{{math|{{sqrt|2}}}}), known as the [[silver ratio]].