Today I learned why the "metric" A4 paper size makes sense.
And I feel bad for our 8 1/2 x 11 and 11 x 14 madness.
A0 paper is one square meter, with dimensions in the golden ratio (1 + sqrt(5)) / 2. Cut it in half, and you have A1 at half a square meter, with precisely the same shape as A0. A2 is half again, then A3, then A4...and they all have exactly the same shape. Whatever you print on one will simply zoom to fit perfectly on the others. And an A3 sheet can simply be split in half or folded to A4 size, etc.
Our madness with 11x14, 8 1/2 x 11, 8 1/2 x 14, 5x7, 4x6 etc. is crazy.
So glad they didn't try to force powers of 10 here, folding, splitting and preserving ratios is so useful.