applied math with sensible units

[trochee]

Apparently, European non-American international paper sizes are all of the ratio √2:1 , with A0 being defined to have a 1m² area. Thus A1 has 0.5m² area, and A2 has 0.25m² area, etcetera. Thus A6 is a postcard and A10 is (at least in principle) 26-by-37mm -- the size of a large postage stamp. In addition, a sheet of Ai paper can be exactly covered by two sheets of Ai+1 paper. (This is a special property of this ratio.) The relatively well-known A4 letter paper is a member of this class, and thus has an area of 2^-4 = 1/16 m².

Thus you can compute the dimensions of any Ai paper by solving the system of equations:

l * w = 2^-i
l = √2 w

This neat interlocking relationship would be really handy (as the link suggests) for easy reductions with a photocopier. American paper sizes, o my foreign reader, have no such elegant relationship to each other known to this author.

[update: unbelievably geeky, but cool: the B series is the geometric means between adjacent A values, and even the C-series (envelopes) follow the same pattern.]

Also, there's a rather tongue-in-cheek (one hopes) explanation for other interesting properties of the A4 paper.

[this post brought to you by trying to print the B5 paper size Computational Linguistics two-up onto American letter paper.]

Comments

[faithhopetricks.livejournal.com]

Ah, now that explains why Russell Hoban is always talking about A4 (I think) yellow paper. Once again, the Rest of the World has a sensible easily understood universally applied measuring system the US just won't buy. ((sighs heavily))

[marnanel.livejournal.com]

I've always loved the A-series. Letter, pschah.

[boobirdsfly.livejournal.com]

Ben oui bien sur : format A4 !

[several-bees.livejournal.com]

Ha to a slightly odd sort of insularity - it never occurred to me that Americans might have to have this explained to them; sure, they might seem to use this odd 'letter paper' thing, but they must all know really, mustn't they, and just be being awkward for the fun of it, and out of habit? Surely?

[boobirdsfly.livejournal.com]

Not to mention inches. INCHES?!!!!