How to Multiply a Positive Integer by a Negative Integer

Math with Mr. J

This educational video by Mr. J provides a clear, concise tutorial on how to multiply a positive integer by a negative integer. The lesson utilizes a digital chalkboard format where the instructor demonstrates the procedural rule—that multiplying integers with different signs results in a negative product—while solving two specific example problems: 4 x (-3) and 20 x (-2). The instructor hand-writes the solution steps in real-time, reinforcing the procedure visually. Beyond simply teaching the rote memorization rule, the video explores the conceptual reasoning behind integer multiplication. Mr. J breaks down the first example (4 x -3) using the concept of repeated addition, explaining that the expression literally means "four groups of negative three." This pedagogical move connects abstract integer rules to foundational arithmetic concepts students already understand, helping to solidify the "why" behind the math. This resource is highly valuable for middle school math classrooms introducing or reviewing operations with rational numbers. It serves as an excellent tool for differentiating instruction, allowing students who need procedural repetition to see the steps clearly, while offering conceptual depth for students ready to understand the underlying logic. Teachers can use this video to introduce the topic, remediate struggling learners, or as a reference for homework support.