The instructor's assistant [electronic resource] : Being a compendium of arithmetic, both practical and theorical, in four parts, containing, 1. Arithmetic in whole Numbers, wherein are all the Rules demonstrated in a plain and easy Manner, having more Questions in each Rule than any now extant, some of which are worked at large, and others with their Answers annexed. 2. Vulgar Fractions, wherein several Things that have been omitted by others, are inserted in a plain and familiar Manner. 3. Decimal Fractions is also treated largely, as also the Square and Cube Roots. A general Rule for extracting the Roots of all Powers-Likewise Interest, Annuities, &c. both simple and compound (after the Method of the late Mr. Ward, but more copious) with necessary Tables to each Rule, shewing the Method of making them, and their Application to Use. 4. The Multiplication of Feet, Inches and Parts, shewn six different Ways; to which is annexed Geometrical Problems, the Mensuration of Superficies, and Artificers Work, in a plain and easy Manner; as also Solids, and the five regular Bodies. To which is added an Appendix in a miscellaneous Way, having a Variety of useful and instructive Exercises to qualify Youth as an Introduction to Trade and Business. The Whole being collected together after the easiest and newest Method, is not only designed for the Use of Schools, but also for the Benefit of all Artificers and others. By John Ross, school-master in Portsmouth.