The modules are written for teachers. They provide the mathematical background to help teachers plan the development of topics in their classrooms. This module is related to Module 24: Number and Algebra: negatives and the index laws in algebra - teacher guide, Module 23: Number and Algebra: algebraic expressions - teacher guide, Module 26: Number and Algebra: linear equations - teacher guide, Module 32: Number and Algebra: fractions and the index laws in algebra - teacher guide, Module 34: Number and Algebra: quadratic equations - teacher guide, and Module 33: Number and Algebra: factorisation - teacher guide.