Counting problems appear frequently in everyday life and are an important part of mathematics. This lesson introduces combinatorics and focuses on two basic counting ideas, the Addition Rule and the Multiplication Rule, in a clear and student friendly way.

Many area problems involve complex figures, but most can be transformed into familiar basic shapes using dissection or equivalent transformations, allowing their areas to be calculated with well-known formulas.

Operations with rational numbers are a fundamental part of junior high algebra, and applying operation laws and techniques can make calculations simpler and more efficient.