Do you know the concept of A-Series Paper...???

The A-series consists of a logical set of paper sizes that are defined by the ISO 216 standard.
# The largest size (A0) measures one square meter...!!
# The height/width ratio remains constant (1:1.41) for all sizes...This means you get the A1 size by folding an A0 paper in two along its shortest side..!!
# Then fold the A1 size in two to get an A2 size paper, and so on…!!
# A-sizes are used to define the finished paper size in commercial printing: A4 is for office documents, A5 is for notepads and A6 is for postcards.