The key to the tutor's guide [electronic resource] : or the arithmetician's repository. Containing the solutions of the questions, &c. in the Tutor's guide. With the references as they stand in the eighth edition. To which is added (where necessary) Some Useful Rules, &c. Likewise an appendix. Shewing the Combination of Quantities; the different Ways they may be varied; with the Method of filling the Magic Squares, &c. The Whole being principally designed for the Ease of Schoolmasters, and, with the Guide, furnishes a more Complete and Extensive System of Arithmetic, than any extant; and will enable all those who are acquainted with the first Principles to attain a competent Knowledge of the several Rules, with Ease and Precision. The sixth edition, carefully revised and corrected By Charles Vyse.