The schoolmasters assistant. [electronic resource] : Being a compendium of arithmetic, both practical and Theoretical. In five parts. Containing, I. Arithmetic in whole numbers, wherein all the common rules, having each of them a sufficient number of questions, with their answers, are methodically and briefly handled. II. Vulgar fractions, wherein several things not commonly met with, are there distinctly treated of, and laid down in the most plain and easy manner. III. Decimals, in which among other things, are considered the extraction of roots; interest, both simple and compound; annuities; rebate, and equation of payments. IV. A large collection of questions with their answers, serving to exercise the foregoing rules, together with a few others, both pleasant and diverting. V. Duodecimals, commonly called cross multiplication; wherein that sort of arithmetic is thoroughly considered, and rendered very plain and easy; together with the method of proving all the foregoing operations at once by division of several denominations, without reducing them into the lowest terms mentioned. The whole being delivered in the most familiar way of question and answer, is recommended by several eminent mathematicians, accomptants, and schoolmasters, as necessary to be used in Schools by all teachers, who would have their scholars thoroughly understand, and make a quick progress in arithmetic. To which is prefixt, an essay on the education of youth; humbly offer'd to the consideration of parents. The twenty-second edition. By Thomas Dilworth, author of the New guide to the English tongue; young bookkeeper's assistant, &c. &c. and schoolmaster in wapping.