Today in Europe and Asia the popular paper sizes are ‘A’ series.The ratio of length and breadth(l/b=√2) in this series is √2. The ratio of √2 in paper size was first noted in 1786 by the German Scientist and Philosopher , George Christoph Lichtenberg.
There are 11 sizes of paper in ‘A’ series(A0 to A10).
A0=1 m2.(A0= 841 mm × 1,189 mm).
A1=1/2 of A0
A2=1/2 of A1
A3=1/2 of A2
A4=1/2 of A3=1/16 of A0=1/16 m2.
A4=210 mm×297mm
And many more…
Did you know ??
The International Paper Sizes (like A3,A4 e.t.c.) are based on the square root of 2.
Photos taken from Wikipedia