How big a piece of paper is needed to cover the entire Earth?
Size of A0 paper: a x b mm^2 where a = 1189 and b = 841
Size of A-n paper = a * (a/b)^n x b * (a/b)^n mm^2
Diameter of Earth = e ~ 12742000000 mm
To cover the Earth, need:
a * (a/b)^n > e
log(e/a) < n log(a/b) so n > log(e/a)/log(a/b)
need n > log(12742000000/1189)/log(1189/841) ~ 46.7
So A-47 paper would be sufficient.