This book provides a comprehensive collection of 66 teaching strategies and ideas to help overcome problems with number, each linked to a specific kind of error described in the related manual. Most of these strategies are classroom-ready and easily implemented. Some are notes for the teacher to read and then plan activities accordingly, and many are activities that can be photocopied for students to use. An index of these notes and activities cross-referenced via strategy number to each error category is given in Appendix 2. Appendix 1 provides reproducible student diagnostic outlines. Topics covered include number systems, arithmetic, calculators, order of operations, decimals, and fractions. (MKR)