The new schoolmaster's assistant, [electronic resource] : or scholar's easy guide to arithmetic. In five parts. Wherein I. The Rules of Addition, Subtraction, Multiplication, and Division, both simple and compound; Reduction and the Rules of Proportion are briefly and methodically considered, and elucidated by proper Examples. II. The mercantile Rules are delivered in a copious and extensive Manner, and diversified with a great Variety of useful Examples. III. The Rules of Alligation, Position, Progression, &c. are laid down in the most simple and easy Manner. IV. The Doctrine of Fractions, both Vulgar and Decimal, are clearly and distinctly treated or: -- To which are added Involution, and Evolution, or the Extraction of Roots. Interest, both simple and compound; Equation of Payments, &c. &c. V. Duodecimals are copiously explained, and applied to Glaziers', Plasterers', Joiners', Painters', Paviors', and Bricklayers' Work, &c. &c. To which are annexed a very large Collection of useful Questions, exercising all the Rules in the Book. Designed principally for the use of schools, and the instruction of youth intended for trade and business. Being an abridgement of the Complete practical arithmetician, with the Answers to the several Questions annexed. By Thomas Keith, Teacher of the Mathematics, Author of a Short and Easy Introduction to the Science of Geography, the Complete Practical Arithmetician, &c. &c.