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5.10 Multiply by 9

Lesson

Are you ready?

Multiplication looks at equally sized groups. Can you solve this problem?
 

$8\times5$8×5

 

Learn

$9$9 groups is $1$1 less than $10$10 groups. Let's look at how we can use this to help us learn the $9$9 times tables.

 

Apply

$5\times9$5×9

 

Remember!
  • $9$9 groups can be thought of as $10$10 groups - $1$1 group.
  • When we look at the answers up until $9\times10$9×10, the units have a descending pattern and the tens have an increasing pattern.
  • When we add the digits in the answers to the nine times tables until we get a single digit, that digit is ALWAYS $9$9.

Outcomes

3.OA.C.7

Fluently multiply and divide within 100, using strategies such as the properties of operations or the relationship between multiplication and division (e.g., knowing that 8 x 5 = 40, one knows 40 ÷ 5 = 8). By the end of 3rd grade, know all products of two one-digit numbers and related division facts.

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