Multiplying Fluently by Subtracting from Groups of 10

This lesson teaches how to multiply fluently by subtracting from groups of 10. It begins with a review of 10s quick facts and the commutative property of multiplication. The lesson then demonstrates how to multiply numbers like 4 * 9, 6 * 9, and 9 * 8 using a strategy that involves subtracting from groups of 10. This approach simplifies multiplication by leveraging known facts and reducing the need for direct calculation.

What is the result of multiplying two groups of 10?

• 20

• 40

• 10

• 30

Which property allows you to switch the order of factors in multiplication?

• Identity Property

• Commutative Property

• Distributive Property

• Associative Property

How do you solve 4 * 9 using the subtract from 10 strategy?

• Subtract 1 from each group of 10

• Subtract 4 from 40

• Subtract 9 from 40

• Subtract 10 from 40

What is the result of 6 * 9 using the subtract from 10 strategy?

• 64

• 54

• 60

• 56

What is the first step in solving 9 * 8 using the subtract from 10 strategy?

• Subtract 9 from 80

• Draw 8 groups of 10

• Subtract 8 from 80

• Draw 9 groups of 8

What is the final result of 9 * 8 using the subtract from 10 strategy?

• 80

• 72

• 64

• 88

What is the main strategy taught in this lesson for multiplying numbers?

• Subtracting from groups of 10

• Dividing groups of 10

• Adding groups of 10

• Multiplying groups of 10