Paper × 841 mm). A1 is half the size of a sheet of A0 (i.e., 594 mm × 841 mm), such that two sheets of A1 placed side by side are equal to one sheet of A0. A2 is half the size of a sheet of A1, and so forth. Common sizes used in the office and the home are A4 and A3 (A3 is the size of two A4 sheets). The density of paper ranges from for tissue paper to for some speciality paper. Printing paper is about . Paper may be classified into seven categories: Some paper types include:
Paper popper Paper popper A paper popper is a party prank that is commonly practiced in public schools. There are many variations of a paper popper, but they all involve a folded sheet of paper being gripped and thrust down. This causes air to be forced into the paper's folded flaps, making the paper flaps pop out in the opposite direction at a high velocity, thus making a loud popping noise. According to popular misconception, the sound is supposed to be caused by the paper breaking the sound barrier. What actually happens is that air rushes in a blast wave to fill