Lesson 7 Build Multiplication Fluency

- Let’s multiply multi-digit whole numbers using the standard algorithm.

Warm-up Notice and Wonder: Same Solution

What do you notice? What do you wonder?

multiply. four hundred seventeen times 28.

multiply. 28 times four hundred seventeen.

Activity 1 Greatest Product

Directions:

Partner A chooses a number card and writes the number in one of the blanks for Round 1.
Partner B does the same.
Repeat until each partner has a two-digit by three-digit multiplication problem.
Find the product.
The partner with the greater product wins a point.
The partner with the most points after 5 rounds wins the game.

Activity 2 Desperately Seeking 9 New Units

Problem 1

Tyler notices that when he uses the standard algorithm and composes a new unit, sometimes there is 1 new unit, sometimes 2, all the way up to 8. He has not seen an example with 9 of the new unit.
For each of these products, how many of each new unit do you compose?

$256 \times 5$
$587 \times 8$
$809 \times 9$

Problem 2

Do you think it is possible to compose 9 of a new unit with the standard multiplication algorithm?

Practice Problem

Problem 1

Andre is playing Greatest Product. He says the greatest product it’s possible to make in the game is $987 \times 65$ . Do you agree with Andre? Explain or show your reasoning.