How to Calculate Percentage Increase

Math with Mr. J

This video provides a clear, step-by-step tutorial on calculating percentage increase, a fundamental concept in pre-algebra and middle school math. The instructor, Mr. J, introduces a specific formula—taking the difference between the new and old numbers, dividing by the original number, and multiplying by 100—to find the percent of change. The video uses a digital chalkboard format where the solution is written out in real-time to model the procedural thinking required for these problems. Two specific examples are worked through in detail: increasing from 12 to 15, and increasing from 50 to 82. For each problem, the instructor explicitly emphasizes the critical step of dividing by the "old" or "original" number rather than the new one, addressing the most common error students make with this topic. The conversion from decimal to percentage is also visually demonstrated by moving the decimal point two places to the right. This resource is excellent for introducing or reviewing the concept of percent change in the classroom. Its direct, distraction-free approach allows students to focus entirely on the mathematical procedure. Teachers can use this video to model the algorithmic thinking required for these problems before having students attempt real-world applications like calculating sales tax, retail markups, or tracking population growth.