Grammage is specified in avoirdupois pounds and the sheet count of a paper ream is usually 500 sheets. However, the mass specified is not the mass of the ream that is sold to the customer. Instead, it is the mass of the uncut "basis ream" in which the sheets have some larger size (parent size). Often, this is a size used during the manufacturing process before the paper was cut to the dimensions in which it is sold. So, to compute the mass per area, one must know The standard dimensions and sheet count of a ream vary according to the
Toilet paper human history dates back to the 6th century AD, in early medieval China. In 589 AD the scholar-official Yan Zhitui (531–591) wrote about the use of toilet paper: During the later Tang dynasty (618–907 AD), an Arab traveller to China in the year 851 AD remarked: During the early 14th century, it was recorded that in modern-day Zhejiang province alone there was an annual manufacturing of toilet paper amounting to ten million packages of 1,000 to 10,000 sheets of toilet paper each. During the Ming dynasty (1368–1644 AD), it was recorded in 1393 that an annual supply of 720,000 sheets