most of the papers that we use for print in general are A4 in size. but most people don't pay enough attention to this. if you pay enough attention you will get to know about a lot of interesting properties about A series of paper sizes and you will also get to learn a lot interesting maths in the process.
A4 is part of a series called A. A4 -> A3 -> A2 -> A1 -> A0. It is part of ISO 216. oh i wish this is ISO 256(would have been poetic)
ISO 216 specifies the width and height of each size in the "A" series in millimeters. The dimensions of each size are defined by halving the preceding paper size along its larger dimension. The size A0 is defined such that it has an area of 1 square meter. Therefore, A1 has an area of 0.5 square meters, A2 has an area of 0.25 square meters, and so on.
so 2 A1 sheets make a A0 and so on.
- A0 is one square meter.
- (2^n) A-n sheets have equal area of A0 that is 1 square meter.
A4 is the most popular one. 16 A4 papers have an area equal to 1 square meter. So when we say that GSM of a paper is 300 gm, we are effectively saying that the weight of 16 A4 sheets is 300 gm.
A4 paper is 210 x 297 mm