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 Fifth 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 School-Masters, 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 fourth edition, carefully revised and corrected. By Charles Vyse, Master of the Academy at Westham-Abbey, Essex.