Thread: WOODWORKING QUIZ for 7 July 04

Originally Posted by bitingmidge

... The A series is cunningly contrived so that starting with A0, if you halve the size of the sheet you get the next size down (A1) and so on...

I'm sure you already know this, but as a matter of minor interest, there is another cunning thing about the A paper series.... A0 has an area of 1 square metre (making A4 a sixteenth of a square metre).

The real clever bit, as you say, is its aspect ratio - merely by folding A3 in half, you get to A4. Hence the weird dimensions, which make no real sense at first glance (A4 = approx. 297mm x 210mm). The aspect ratio that enables this minor miracle is 1.414:1 (square root of 2). So A3 is 420x297, etc...

Folding American paper sizes in half produces a completely different aspect ratio, making photo-reduction very difficult.