Here is some interesting reading and a useful reference for anyone who deals with paper…
A discussion about [url=http://www.cl.cam.ac.uk/~mgk25/iso-paper.html]International Standard Paper Sizes[/url]
Something I didn’t know was:
In the ISO paper size system, the height-to-width ratio of all pages is the square root of two (1.4142 : 1). This aspect ratio is especially convenient for a paper size. If you put two such pages next to each other, or equivalently cut one parallel to its shorter side into two equal pieces, then the resulting page will have again the same width/height ratio.
The ISO paper sizes are based on the metric system. The square-root-of-two ratio does not permit both the height and width of the pages to be nicely rounded metric lengths. Therefore, the area of the pages has been defined to have round metric values. As paper is usually specified in g/mÃ¯Â¿Â½, this simplifies calculation of the mass of a document if the format and number of pages are known.
It all starts to make sense now !