Page:Paper and Its Uses.djvu/162



To find the Cost of Paper.—The methods of calculation of cost will depend upon the number of sheets to the ream. If packed in 480's, and the quantity is stated in reams, quires, and sheets, the cost is obtained very easily. Paper at £1 per ream is 1s. per quire, $$\tfrac{1}{2}$$d. per sheet. Take 110 reams, 17 quires, 12 sheets, at 7s. 6d. per ream. At £1 per ream this equals £110. 17s. 6d.; and at 7s. 6d. this comes to $$\tfrac{3}{8}$$ of that sum = £41. 6s. 7d.; or reckoned at 110$$\tfrac{7}{8}$$ reams at 7s. 6d., the same figures are obtained. When reams containing a larger number of sheets are concerned, the calculation is made on the number of reams plus the fraction of the ream.

Prices and Weights of Boards.—To obtain the price per 480 when the price per gross is given, multiply the figure by $$\tfrac{10}{3}$$. Per 500 is taken as 3$$\tfrac{1}{2}$$ times the price per gross. When the price is given per 480, the price per gross is $$\tfrac{3}{10}$$ of that amount. If the price is given as per 500, the gross will cost $$\tfrac{2}{7}$$ of that amount. Weights are calculated on the same basis. To Calculate the Weight of a Paper from the Size and Weight of another Paper.—A table of equivalent weights papers of regular sizes based on demy of certain weights is given on pages 144-45. To find the weight of other sizes, multiply the weight of the ream in pounds by the area of the new size in inches, and divide by the area of the size, the weight of which is known.

Example.—The weight of large post is required equivalent to double foolscap 30 Ib.

If the table of equivalent weights be examined, it will be seen that the area of large post is 346 $$\tfrac{1}{2}$$ square inches, and