For a full dissertation on the subject of ISO 216, click here: http://www.cl.cam.ac.uk/~mgk25/iso-paper.html.
You'll note that the A series is only one of several (all equally rational) in the ISO 216 standard. Bill Potts, CMS Roseville, CA http://metric1.org [SI Navigator] >-----Original Message----- >From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] >Behalf Of David King >Sent: Friday, June 25, 2004 15:00 >To: U.S. Metric Association >Subject: [USMA:30213] A series paper - quick tutorial > > >While most of the world uses the A series of paper, the USA continues on >with its own sizes (e.g. Letter). Canada also has its own proprietary >paper sizes. > >The international A series is very easy to use. The ratio of the sides >is always the square root of 2, i.e. divide the length by width and it >will ALWAYS equal 1.414. This also means that when a piece of A-sized >paper is cut in half along the longest side, the new smaller sheet will >have an area that is half the original, and with the ratio of the sides >being still the same. This means that, for example, you can stick two >pieces of A4 paper together along the longest side and it becomes one >sheet of A3, or vice versa, cut an A3 sheet into two A4 sheets. > >To calculate the area of any A-series sheet, use this simple formula: > >area (in square metres) = 1 / (2^n) > >where n = value of paper size, e.g. for A4 paper, n = 4 > >thus area = 1 divided by ( 2 raised to the power 4 ) = 1 / (2 � 2 � 2 � >2) = 1/16 >so an A4 sheet has an area of one sixteenth of one square metre. > >Look at A0, put in the 0 and the formula is: area = 1 / (2^0) = 1/1 = 1 > >A0 has an area of one square metre. > >The sizes increase in number by 1 as they halve in area, thus the series >goes A0, A1, A2, A3, A4, A5, A6, etc. > >The A series of paper is mathematically perfect as well as being very >useful in offices around the world where it is used, because of its >ability to retain its shape when halved or doubled in area. US paper >sizes cannot do this, as the ratio of sides is not 1.414.
