Multiplying Whole Numbers

Review of 4th Grade Standard and 5th Grade Standard

4.NBT.B.5 - Multiply a whole number of up to four digits by a one-digit whole number, and multiply two two-digit numbers, using strategies based on place value and the properties of operations. Illustrate and explain the calculation by using equations, rectangular arrays, and/or area models.

5.NBT.B.5 - Fluently multiply multi-digit whole numbers using the standard algorithm.

Go Math Lesson Video - Chapter 2

Lesson 2.1 (This video is from a previous version so the lesson number is different but the content is the same.)

Below are videos for reviewing multiplication strategies based on place value. Students should have learned some of these strategies in 4th grade, such as area model, multiplying by decomposing numbers, using the distributive model and partial product multiplication. Even if your student can solve problems using the standard algorithm, it is important for them to understand why the algorithm works, and be able to solve problems in more than one way. So try problems using each of these strategies! As you review the videos with your student, once you start to understand, see if you can stop the video at various points and see if you can solve the next step before they do. Videos for learning the standard algorithm are below the divider line.

Multi-Digit Multiplication Strategies

This video does a nice job of showing the area model.

Multiplying with area model: 16 x 27Sal uses an area model to multiply 16x27.

This video does a nice job of tying the area to the standard algorithm so that you can see how they relate.

This video shows a 3 digit by 2 digit problem being solved using the area model.

This video shows the decomposing strategy. This is a great mental math strategy as it is very flexible once you start using

Multiplying with distributive propertySal uses the distributive property to multiply 87x63.

Here is an example of multiplication using the distributive property. How does this relate to the area model or any of the other multiplication strategies? Do you see any similarities? Watch the next video on partial products? Do you see any connections between these strategies?

Here is the standard algorithm applied to a 3 digit by 2 digit problem.

Here is the same person as the previous video connecting the standard algorithm to the area model.

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