Units of paper quantity Simon Winchester, in "The Surgeon of Crowthorne", cites a specific number, defining quire as "a booklet eight pages thick." Several European words for quire keep the meaning of "book of paper": Ger. "Buch von Papier", Dan. "bog papir", Du. "bock papier". In blankbook binding, "quire" is a term indicating 80 pages. A ream of paper is a quantity of sheets of the same size and quality. International standards organizations define the ream as 500 identical sheets. This ream of 500 sheets (20 quires of 25 sheets) is also known as a 'long' ream, and is gradually replacing the old value
Paper size any size can be made by using sheets of the next larger size, e.g. A4 sheets are folded to make A5 brochures. The system allows scaling without compromising the aspect ratio from one size to another—as provided by office photocopiers, e.g. enlarging A4 to A3 or reducing A3 to A4. Similarly, two sheets of A4 can be scaled down and fit exactly on 1 sheet without any cutoff or margins. The behavior of the aspect ratio is easily proven: on a sheet of paper, let "a" be the long side and "b" be the short side; thus, = . When