Calculating the Whole Amount from a Percentage Part

MatholiaChannel

This instructional video demonstrates the "unitary method" for solving percentage word problems where the goal is to find the whole amount given a specific part and its corresponding percentage. The video walks through three distinct real-world scenarios: calculating the original price of a phone based on a discount amount, determining a weekly allowance based on savings, and finding a total school population based on the number of students playing sports. The content focuses on a consistent three-step algorithmic approach: identifying the known percentage and value, dividing to find the value of 1%, and then multiplying by 100 to find the whole (100%). This systematic repetition helps reinforce the logic behind reverse percentage calculations, moving beyond rote memorization of formulas to conceptual understanding of proportional reasoning. For educators, this video serves as an excellent direct instruction tool for introducing 6th and 7th-grade students to reverse percentage problems. It provides a clear visual model for setting up equations and executing mental math strategies (like dividing by 20 by splitting it into dividing by 2 and then 10). The real-life contexts make the abstract math relevant, demonstrating how these skills apply to shopping, budgeting, and analyzing statistics.