This topic focuses on calculating 20% of various numbers, working on the concept of finding a specific percentage (a multiple of 10%) of given values. Each problem poses the same task – to determine what 20% of a stated number is, offering multiple choice answers to select from. The skill practiced is a basic application of percentage calculations, which is part of a broader unit on percentages. This math concept helps develop a foundational understanding of percentage operations, usually necessary for various practical and academic applications in mathematics.