How to Add, Subtract, Multiply, and Divide Decimals

Math with Mr. J

This educational math video provides a comprehensive review of the four basic operations with decimals: addition, subtraction, multiplication, and division. The instructor, Mr. J, walks viewers through four distinct practice problems, dedicating one problem to each operation. He explicitly models the step-by-step procedures required for each, emphasizing common student stumbling blocks such as lining up decimal points during addition and subtraction, using placeholder zeros, and correctly placing the decimal point in the final answer for multiplication and division. A key pedagogical feature of this video is the instructor's insistence on checking the reasonableness of answers through estimation. After solving each problem algorithmically, he pauses to round the original numbers and performs a mental calculation to ensure the final result makes sense. This reinforces critical thinking habits over rote memorization of algorithms. The visual style is clear and focused, utilizing a digital chalkboard format where the operations are written out in real-time, allowing students to follow the handwritten process exactly as they would on their own paper. This resource is highly valuable for upper elementary and middle school classrooms as a revision tool or a flipped classroom resource. It effectively addresses the distinct rules for decimal placement across different operations—a common source of confusion for learners. Teachers can use this video to differentiate instruction, allowing students who struggle with specific operations to review just those segments, or as a whole-class refresher before a unit test on rational number operations.