How to Teach Partial Products Multiplication

Memorizing multiplication facts is the first step to understanding how to multiply. For years, schools taught students to multiply multi-digit numbers using the traditional method. The traditional method of multiplication involves crossing out numbers, adding on zeros and carrying numbers. Partial products multiplication is a new strategy teachers are using to teach place value and provide an alternative strategy to find an answer to two- and three-digit multiplication problems.

Instructions

1. Review place value with students for the ones and tens digits. Explain that for the number 26, the 2 stands for two tens, or twenty, and the 6 stands for six ones. Tell the students that the answer to a multiplication problem is called the product and the numbers being multiplied are called the factors.

2. Write the example 26 x 32 on the board. Explain that the number 26 is equal to 20 + 6 and 32 is equal to 30 + 2. Write this to the side of the problem.

3. Write 20 x 30 = 600 under the answer line. Explain that you multiplied the tens place in both factors.

4. Write 20 x 2 = 40 under 20 x 30 = 600. Explain that you multiplied the tens place in 26 and the ones place in 32.

5. Write 6 x 30 = 180 under 20 x 2 = 40. Explain that you multiplied the ones place in 26 and the tens place in 30.

6. Write 6 x 2 = 12 under 6 x 30 = 180. Explain that you multiplied the ones place in both factors.

7. Write 600 + 40 + 180 + 12 to the side of the problem. Ask the students to add these numbers. Ask for volunteers to share their answer. Tell students the correct answer is 832.

8. Multiply 26 x 32 on the board using the traditional multiplication strategy. Show students that the answers with both strategies are the same.

9. Model another example on the board, such as 45 x 56. With students' help, find the product. Have the students practice problems independently. Check to make sure they have the correct answer after each problem. Ask volunteers to come up to the board to show their work and explain how they found the correct answer.

References

• Everyday Mathematics